iPhone vs. Android
The smartphone universe, as you are probably aware, is split between two major camps: iPhone and Android. But these two terms don't really describe the same thing.
The word "iPhone" is a product brand name denoting a phone that Apple, and only Apple, makes.
The word "Android" doesn't even refer to a phone at all. It's the name of an operating system (OS) that just so happens to run on most non-Apple phones. Google owns Android. But there's lots of companies that make phones and other devices like smart TVs that use Android.
Samsung is the largest maker of Android-based phones in the US market, distantly followed by Google themselves, Motorola, Nokia, and a few others.
A Small Bit of History
Although comparatively primitive multi-function phones like the BlackBerry already existed, Apple unquestionably ushered-in the modern smartphone era when it released the iPhone in 2007. It was a revolutionary device that caused nothing less than a tectonic shift in consumer computing and communication. It truly brought useful mobile access to the masses in a way that previous devices never could.
Here was a company (Apple) that managed in considerable secrecy to create the device itself, a number of useful applications, and the operating system on which it all ran. Every other phone maker was caught flat-footed and struggled to bring to market their own smartphones. No one was even close and they all pretty much failed.
At that time Google had owned Android from a 2005 acquisition and was developing a mobile OS. The introduction of the iPhone put Google's efforts into overdrive, speeding up development and giving them a template (by copying iPhone's look and feel) to success.
Rather than try to quickly cobble together its own phone, Google instead wisely chose to license Android at no cost to existing phone makers who were already in a better manufacturing position to pivot to a smartphone design in the style of the iPhone. Google would control the OS (Android) which is where the real money would eventually be made in search and advertising.
Modern Times
The smartphone market is quite mature these days. Pretty much everyone has a smartphone. It's an integral part of life, seemingly no less important than clean air, water, food, and shelter. People are more likely to have a smartphone than a regular computer, a car, a bicycle, or even a place to live. Yes, most homeless people have phones even if only a low-cost prepaid model. It's the most commonly owned consumer item if you don't count clothing.
That's because a mobile phone is essential to functioning at any level in today's society. Many of the services that people, including the homeless, need to access must be conducted online. At the very least, you need a smartphone to do that.
Pros and Cons
OK, as implied by my "iPhone vs Android" title, here's a list of the pros and cons between the two major smartphone ecosystems. I'll list the feature or function, then describe how iPhone and Android fares on that.
Cost
Apple really doesn't offer many down-market options. All their products are considered premium and so are pretty costly. But even at that high level, Apple does offer somewhat less expensive models. Less memory, non-pro editions, previous model year, etc.
Buying a used iPhone on sites like Gazelle and Swappa can be a money saver compared to buying new and you'll still get a decent phone.
Android models, on the other hand, span a range from low-end budget models all the way to niche and concept models that can exceed Apple's most expensive models. In this way, Android has more variety in both niche features and a wide price range. You can buy a fairly decent new Android phone for $200 easily.
Advantage: Android
Updates
It's really important to be using a supported phone. "Supported" here means the phone receives updates from the manufacturer. These may be feature updates, bug fixes, and security updates. An unsupported phone, especially since it's not receiving security updates, is riskier as it may become vulnerable to newly discovered malware.
Apple really shines here by supporting iPhone models going back six or even eight(!) years. That's a remarkably long support tail. Additionally, since Apple manages the entire iPhone stack top to bottom then it generally releases updates faster and more often, making sure iPhone runs optimally.
Android is sorely lacking this regard. Updates take longer to be deployed and are much farther apart time wise. Android phones usually have a much shorter support tail as well. Perhaps as few as two years depending on the make and model of the particular phone. If you're lucky, you'll get maybe four years.
"So why's that a big deal? Who keeps a phone longer than 2-3 years?"
Answer: Lots of people. It's not like the smartphone early days when each new year brought revolutionary changes in storage, performance, and other features. These days, annual updates are more evolutionary. A fair number of people keep a phone for 4-6 years.
Another benefit to a long support tail is a higher resale value. Selling your existing phone after upgrading to a new one will be easier and bring more money if there's still some support life remaining. With Apple's six year support minimum, you can keep a new iPhone for three years and it'll still have three-plus years of support life when you sell or give it away.
Advantage: iPhone
Privacy
One of Apple's well-known selling points (true or not) is its focus on customer privacy. Apple isn't primarily an advertising or search company. It doesn't focus as heavily on selling ads, selling metadata, or behavioral metrics to big data so it can afford to be more consumer-friendly in this regard. They earn most of their money from making and selling their devices, app store commissions, and various optional subscription services.
That's not to say Apple doesn't do any of these things as they most certainly do but some tech research suggests that Apple is probably not as bad. No big tech company willfully admits the full extent of their data collection and that includes Apple.
Google, on the other hand, is an advertising and data-mining Goliath, which Apple isn't. Google monetizes Android by collecting and using metadata about how you use your phone. Google monetizes the Chrome browser similarly but that's another topic. A lot of ink has been spilled enumerating how Google (ab)uses your privacy. You can find a lot to read on this simply by, erm, googling it.
In short, no big tech is great on privacy. Of the big boys, Apple is probably the best of that lot, but that's not sayin' much.
Advantage: iPhone, but narrowly
Security
Smartphones are generally more secure than desktop computers due, in part, to their comparatively cloistered nature. Unlike desktop-class operating systems like Windows and MacOS that were designed in the laissez-faire days before the rise of the internet and the malware that came with it, today's mobile operating systems are designed from the outset with mature security architectural concepts in mind.
But that doesn't mean they're equal.
The iPhone operating system is more locked-down. App developers are more restricted with what their programs can access. Also, since iPhone receives more updates and receives them sooner, any vulnerabilities discovered in iOS (iPhone Operating System) can be patched sooner and rolled-out faster.
Apple also has a better track record at keeping malicious apps out of their app store. Not spotless, but better.
Advantage: iPhone
Geek Appeal
Apple is too closed and locked-down for most computer geeks and hobbyist experimenters' tastes. Apple does not allow unauthorized code to execute or user-initiated changes to be made to their platform no matter how advanced the user is. Apps can only be installed from the App Store with a few exceptions for large, enterprise users.
Otherwise, iPhone is a completely closed ecosystem. No hacking-type activities permitted. That's a good thing for ordinary users but maybe not for some geeks who may prefer a device they can modify outside of the manufacturers control.
Android, on the other hand, is pretty easily modified. Some Android phones allow loading custom ROMs which is basically a brain transplant.
Many models allow the user to sideload -- which means installing apps from 3rd party repositories, not just the Google Play Store. Sideloading brings significant risks so it's disabled by default. But it can be enabled by those who understand and agree to the added risk.
Even though I'm a computer geek, I still prefer and use the iPhone. And many computer geeks feel similarly for the reasons I gave above. To me, the phone is a tool and not an experimental playground. I have no desire to hack my phone.
Advantage: Android, for geeky reasons
Upgrading After Purchase
Sadly, neither iPhone nor Android* models can be upgraded with additional storage after purchase. So after deciding on which phone to buy, your next most important decision is how much storage you want. I recommend getting at least 256 GB of storage and as much more as you can easily afford. Pics and especially videos really chew up storage. The less storage you have on the phone the more often you'll have to export and delete some of those pics and videos.
* Some Android models have a memory card slot that lets you add storage. But this feature, never having been universal, is becoming ever rarer today. But even then, add-in memory cards don't really behave like regular storage. It's not as fast or easy to use. It's like adding a second hard drive to your computer. Yes, you'll have more storage, but that storage is separate from the main storage and using it takes a deliberate effort that most people will not do properly nor understand.
Advantage: Neither
Closing
The iPhone in my opinion is probably the better choice for regular people who just want to do their jobs and live their lives for all the reasons I gave above. But really, you'll do fine with either one.