I don't agree with either. There is far too little incentive to go to a sub-forum just to give people recommendations. You will generally only go there to get recommendations. Thus it would just become a noobs feeding ground.
One thread I think is also a bad idea (although better than one forum). This is because they become too long and hard to keep up with. I guess there would be advantages of having ALL recommendations in one thread (convenient for starters), but I think genuine participation would dissipate.
The best way to keep this place brimming and interesting is continual rolling threads - which whilst most topics will recycle, you can have slight variations and breaks in discussion. To do this, you have to allow natural selection in the forums, i.e. people getting told when they are participating in a non-constructive manner. As ironic as it seems to have non-constructive criticism stop non-constructive posts, it is the most efficient form of forum moderation (short of a decent / regular moderator, which I thought was working with GoD, but didn't work with JP).