"(...) Pattinson would make an excellent Buckley, as not only does he physically resemble the singer, but he also possesses the same kind of ethereal vibe that Buckley carried. His popularity was mainly rooted in his music, but he also had a mysterious quality that made him a fascinating character. Can Pattinson sing as well as Buckley? There's no evidence to suggest that he can. However, it seems like the man who breathed life into Edward Cullen can handle the moody, romantic vibe that Buckley gave off. Take a look at this performance of "Forget Her" (recorded during the Grace sessions but not released until 2004) and see if you can't picture Pattinson sliding into that role" (access here)
What's MTV's take on Franco and those shortlisted as possibilities for the role:
"Franco has probably played too many iconic roles to play Buckley (he's created so many great fictional characters that it'd be hard to accept him as playing a real person) and James Marsden (of "X-Men" fame) doesn't have that same air of mystery. Leto would probably be a good choice, as he has the musical chops to go with his left-field approach to performances"