The PhenomII 550BE coz you can get a good 785G DDRIII mobo for 5-6k and DDRIII is the way to go now istead of buying a new LGA775 socket.
If you can wait til Jan then new 32nm fab core i-3 processors are going to be released by intel. They core i-3 are priced from $125. So that should be a good option worth waiting.