I have a desktop, laptop and I Pad. Each is used differently. The desktop , with good soundcard and Windows Media Centre (can watch TV whilst working) is used the most for all issues, but particularly for music, photo editing (Photoshop) and e mails that need printing. The Laptop can do many of these things, but the screen is smaller, and there is no second drive built in, and printing is a little more difficult. For those who do not "manipulate" music or pictures the iPad is OK - limited storage of media, e mails etc and a little more awkward when surfing - especially when participating in forums etc. In your case, as you have an iPhone already (a bit like a small iPad) and you do not need the more complex programmes, I would have thought a laptop plus USB drive for back up might be the best choice. A good iPad is about the same price as a laptop, and I think you get more versatility and "bangs for your bucks" with it.
HTC U12 Plus review: Hands-on