Whether Google would prefer it one way or another, we can only guess. An entire snake oil industry is built around optimising sites for high search rankings, but in the end, the biggest contributor to your ranking is whether or not you have fresh, user-generated content...
Frankly, a forum is hands-down the best way to expose and incentivise user-generated content for indexing. Everything else (meta tags, URL structure, etc) is just icing on the cake.