Dont know if this really helps, may be more confusing than anything but its a little map I built up of places while I was at uni there, there is also a lot more than is marked on here but unfortunately not really marked on maps so required a bit of hunting/exploring to find to link up to a good loop so again you probably are best finding someone to follow with a bit of local knowledge.
Kirkhill is pretty good, not the shitey man made stuff which is about 3 rollers and 2 berms but if you go away exploring in the woods you can find some quite decent stuff, personally I found some better natural trails in the woods that are on the opposite side of the dual carraigeway to the main car park.
Scotly is great, if you dont have someone to follow I would say just go up to the tower at the top of the hill and if you look back down towards Banchory there are some trails away down to the right behind you kind of direction.
Bennachie is the range of hills that Pitfichie is part of, that includes the hills you can see for miles around that has the hill that looks like is has a big nipple on the top. Pitfichie has two tracks but isnt great but if you do those and also have a go at the xc route up round Cairn William thats a decent day/evening out. There is an FC map online. There are a lot of tracks on the rest of the hills around there... Milstone, Mither Tap and Oxen Craig but a lot of them are properly surfaced and fulllll! of drainage ditches, I would recommend the track that runs North off Milstone (No. 9 on the map below) and also the path that runs North off Oxen Craig (No.3 on the map below.)
Or if you are feeling adventurous go and have an explore up some tracks away up the dee valley! Some EPIC scenery and valleys to be had up there. I could go on but you might be getting bored by now... If you want some more specifics let me know and ill see if i can help (unfortunately dont live there any more otherwise I would show you around)