Acording to all of you Ramis seems to be the obvious choice but:
1) Reitman was the director of the first two films and made an excelent job!
2) They both have their ups and downs.
and 3) I haven't seen Raims act a major role for a long time now. So if he's to have a lot of screen time then somebody has to direct him I guess.
But I wouldn't mind either of them, or somebody completely differen for that matter, JUST AS LONG AS THERE IS A MOVIE TO BE DIRECTED!