It's a tough one
If you took away the first 5 games of the season and looked at Wilson's play over the last 9 games and extended that over the course of a season, I'd say no doubt. But those first 5 games simply weren't great.
That said, New England, Detroit, Miami, Chicago x 2, I don't ever remember Hasselbeck driving down the field for a go-ahead TD with <5 minutes left 5 times in a single season (even if 3 of those leads were lost or tied in the end), nor do I ever remember a Hasselbeck-led team putting up 50 points in a single game, let alone 2 in a season (even if Wilson was not the major factor in the Arizona game).
Right now I'd say it's a tie between Wilson and Hasselbeck.
It all comes down to this weekend's game. If Wilson can post a 90+ QB rating and a win against the NFL's consensus number 1 defense (even though I still prefer ours), and lead the team to victory against the Rams, then I think it has to go to him, regardless of the playoff results