If you _need_ more space than it comes with, then you'll want something with an SD card, but otherwise I wouldn't worry about it.
Frankly, at this point I wouldn't have any Android phone that wasn't a Nexus. So when I replace my Galaxy Nexus (another year or so) then I'll be looking to see what the successor to the Nexus 4 is. If I was buying next week I'd definitely get a Nexus 4.