I have, and still do, run a GTR server. More GTR2 now though.
I have run servers for LFS, GTR, GTR2, rFactor, GTL and netKar, and I have driven on all of them.
Each sim has good points and bad points as you would expect.
Sometimes I'll drive some laps on netKar, decide to try a few online races in LFS, Wednesdays and Sundays it's GTR 2 with the ERG.
Comparing sims is non-productive in my opinion because I like them all and I'll use them all, depending on what I feel like racing. Each has good points and bad points but it's all relative to personal taste in my experience.