One thing I don't see covered much is not just that a laptop can do that an iPad can't (and vice versa), but also how well those tasks get done.
I can't quite explain it, but I find that iOS apps have a certain simplicity and elegance to it that I find lacking on desktop apps. For example, launch a drawing app on an iPad and it's literally all screen. It's just this giant canvas which allows you to just focus on drawing. Conversely, launch a drawing app on a PC (windows or Mac), and there are all these menus everywhere, and you are left with maybe ½ the screen left for actually drawing?
Same thing with word processing. I get that Office is a universal standard, but it comes chock full of features and settings that most people won't ever need. Till now, I don't understand why Microsoft hasn't done what Apple did with iworks and moved the menu settings to the side, rather than park all of them on the top (since on a 16:9 laptop, you typically have more horizontal screen space than vertical). I find I am so much more comfortable typing on my iPad + Smart Keyboard, where text editing apps are a dime a dozen (pages, notes, bear, drafts, just to name a few). And when I want a take a break, simply detach my iPad from the smart keyboard and lean back, walk around or go sit somewhere else, where the iPad remains a very capable tablet, unlike windows.
Other apps like mind mapping just feel so much nicer on an iPad. Notability is a cheap app that lets you manage and annotate on PDF files. Scanner pro for scanning documents. There's even an app if you want to quickly email a webpage to yourself. With the huge array of apps available for the iPad, chances are you are more likely to find that one specific app which lets you do something you want on iOS compared to a PC. There's also the shortcuts app, if you are willing to invest the time to automate a certain workflow.
The iPad just feels like the best package of battery life, portability and ease of use overall.