Waves Trans-X is pretty good. I've gotten some mileage out of the "more snare", "more stick", "mega kick", and "more punch" (on overheads of all things!) presets, but I find myself not using it as much now that I'm getting better at micing, eq, and using more "standard" compression.
In a roundabout kind of way, I always do some transient shaping on snares by throwing a c4 on it and shaping the sound by boosting or cutting the bands. It's roundabout transient shaping in that you can definitely change the perceived attack of the track by boosting or cutting a few db here or there. Great for getting rid of that harsh "paper" snare attack.
Never heard of Transient Designer. Damn, I really do learn something new here everyday.