Kirroughtree is my new favourite, followed by Dalbeattie then inners/GT, but then i have ridden inner/GT many many times as it's just down the road so maybe the novelty factor needs to be taken into account.
Ktree because the trail has a fantastic mix of fast and swoopy and technical and rocky, everything catered for.
DBT because it is pretty flat but you need to work through all of it and then it throws some really nice stuff at you.
GT red bit of a motorway but fast and fun the black is always entertaining.
Inners xc is just a lot of fun and there's massive opportunity to explore off the top of the Minchmoor and returning to the trail on the return.