Well, I've only ever used Proboards before, and I'm sure a lot of you are more used to that, but Forumotion seems like it has great potential, and I thought long and hard before actually starting to build the site here on Forumotion.
Plus sides for Forumotion are it has a hell of a lot more admin functions etc., it has in-depth statistics on the forum, you can change the forum link at any time, you can create a portal to be your homepage before entering the forum, and a load of other stuff too which I can't really remember right now lol, but you should be able to see some of the stuff for yourselves anyway
Plus sides for Proboards are you can create multiple skins, wheareas on Forumotion you'll just have to edit the same skin (I think, unless there is a way which I haven't worked out yet) and you can edit moderator powers more in-depth.
Other than that, I've spent a lotta time working on this site already, it wouldn't be nice to have to start again, but if you feel this site would be better on Proboards then please make yourselves heard here.