I don't need usb ports or stylus on my tablet. I do appreciate that other people do need them, but I don't. If the Surface 3 were lighter than the iPad, I might be interested, but for me, lighter tablet trumps full PC.
It's just that, if I'm going to be doing any extended typing, it'll be at a desk, and if I'm going to be at a desk, I might as well have a real full PC. In my view, tablets are at that awkward stage we had once with laptops, where laptops were almost powerful enough to replace desktops, but not quite. In a few more generations, I think tablets will get to the point where it really is a no-brainer to have them be full PCs in tablet form, but at the moment, there are still compromises to getting a full PC into a tablet form factor. So I suspect I'll be sticking with the iPad for a few more years, at least.