Ultra Portable: iPad or Surface Pro
If you travel a lot or like to travel as light as possible, you'll want to select a thin and lightweight device that does what you need it to do. Yeah, that's pretty obvious, right? But the platform and device you choose determines a lot about the experience you'll have and what you can do with it.
For this article, I'm focusing on two platforms for ultra light, mobile computing. Windows (in the form of the Microsoft Surface Pro) and Apple's iPad. There are other platforms (Android) and other highly portable Windows-based solutions other than the Surface Pro. But these two devices represent what I believe to be the pinnacle of ultra lightweight mobile computing so this is what I'm focusing on in this article.
Surface Pro
The Surface Pro 4 is full-fledged Windows computer running Windows 10 Professional. You can do most any non-gaming thing on the Surface Pro that you can do on your Windows tower computer. The Surface Pro is essentially a laptop that can also behave like a tablet. It has a surprisingly good magnetically detachable backlit keyboard with touchpad.
You can run Quickbooks, full editions of Microsoft Office (that's Word, Excel, Outlook, etc.), and most other software that you'd run on a full-sized tower computer. The Surface Pro is available with a mobile version of Intel's high-end i-series processors so there's not much performance compromise.
Using cloud file sharing solutions like Dropbox, Google Drive, or OneDrive, you can access all your files that you use in your office. The Surface Pro lets you bring your entire computing world with you with no functional compromise.
Detach the keyboard and you can use the Surface Pro as a (relatively heavy and thick) tablet. The Windows App Store has plenty of apps in it although perhaps not quite as well stocked as Apple's App Store.
Apple iPad
The iPad, on the other hand, runs iOS which is Apple's mobile operating system. It's the same OS that runs on the iPhone so in this way the iPad is essentially an over-sized iPhone, but without the phone. It's not a fully-functional computer in the same sense as a Macbook Pro or a Windows laptop like the Surface Pro. It's a tablet first (and only) so it's better and more convenient at being a tablet than the Surface Pro.
As a tablet-only device running a mobile-designed OS, the iPad's power management is excellent. You rarely need to power it off. Just charge it each night as you do your phone. Since the iPad is not a "full-fledged" computer then it can get away with a less powerful CPU and supporting chipset which makes the entire device lighter, thinner, and run longer on a charge.
Being an iOS device, you can download and run software only from Apple's App Store. You cannot run any "desktop" computer software. However, the App Store has a ton of useful software with many productivity products mimicking their desktop equivalents.
Another advantage to the iPad is the availability of built-in cellular communication. This lets you go online without having to find a random wi-fi hotspot. It's always online just like a smart phone except where it isn't like on an airplane. Do not underestimate the usefulness of this capability! Many an iPad owner has regretted not buying a cellular-enabled iPad! It's far less hassle to have always-available internet access built into the device than having to find an open wi-fi or trying to hotspot off your phone.
The additional cost for a cellular-enabled model is well worth it and you cannot upgrade later. In fact, nothing about the iPad (or Surface Pro) is upgradable after purchase. All decisions regarding built-in specs must be made at time of purchase.
Other Devices
Android: I don't generally recommend Android devices to my clients, period. Why is that?
Chromebook: It's sort of like a low-powered laptop that runs Chrome only. In my opinion, it embodies all the disadvantages of a laptop with no upside. It can't run Windows software and it's not a tablet. And it's useless without the internet.
The Chromebook is too much of a departure from the familiar ways most of us use computers and is too much of a functional compromise. Many people have bought the Chromebook thinking it was a low-cost laptop. When they finally figured out that it's nothing more than an internet terminal, back it went. Return rates are higher than average for this very reason. It can be useful and sufficient, but only if you fully understand how it works, what Google had in mind when they designed it, and if it fits your use-case. Not likely.
If you are struggling with a decision whether to buy a Chromebook or a regular laptop then chances are good you are not familiar enough with its limitations. Buy a regular laptop instead. There's nothing a Chromebook can do that a laptop cannot do.
Help me Choose
Consider what you need to do on your portable device while travelling or just away from the office for a few hours. If your needs are mostly online such as accessing email, web browsing, watching a video, etc. then an iPad is probably the best option. It's cheaper, lighter and more convenient than the Surface Pro.
But if you need the capabilities offered only by a full-fledged computer, such as running the full versions of Word, Excel, Outlook, etc. or other business software that must be loaded on the device itself, then a Surface Pro is a must. These are things the iPad cannot do.