Dalbeattie- excellent, and probably the best. Rocks, not too strenuous, long, enjoyable, proper descents none of this traversey nonsense.
Inners- again very good. Loooong climb, proper descent apart from one bit near the end that's a bit bobbins.
Kirro- good, a long ride that will tire you out. Very enjoyable in a non-tech way.
Glentress- hit and miss. Somedays it's fun, somedays it's gash. You really need to rag it to get the most out of it I find and if you're not on top of your game it's ultimately a let down- it's just not that much fun when you're not going as fast as you can. A lightweight XC bike helps, though.
Mabie- very tame, very dull, can get muddy. Unless you can do the Darkside in which case it's the most difficult and rewarding trail centre experience there is.
Ae- just awful. Bizarre in that there's a huge amount of climbing and very little proper DH. Badly built, badly maintained, no fun whatsoever.
No ridden Newcastleton or Glentrool.