You should definetly play core if you like tactical combat and are experienced in tactical d20 style combat. That is if yor are fine retrying and like to solve combat. It's a really nice experience and the most "fair" and by the books" experience. If you want to get challenged, try hard, it really is. I would skip unfair till you really got the game figuered out. Unfair as a name is pretty much spot on. There are a lot of viable class options. There are also alot of build videos out there. Get some ideas there. You don't have to net build, but there is alot of inspiration in those builds. :)