My Nokia n91 4Gb hang anytime i replace the battery cover. All u need to do is to have a software update or your n91 phone by using nokia suit update an your.
1) You can always wait six months and something newer will come out. Heck, the 3GSM show in Barcelona is opening soon, and you can bet a raft of new phones will be unveiled there. And then a few months after that. 2) I'm amused that you're asking about two phones that haven't been released anywhere yet. Are you in the US or Europe/Asia? I haven't seen either of those phones getting FCC approval yet, though I don't haunt the FCC site as a rule. 3) Don't ask what's 'better' unless you can define what's 'better' to you.
Tell us so we can match your specs.