I've handled all 3, and own the Buck/Mayo. I will own the Skirmish, but I will not own the ATR.
Buck Mayo: It is a great "gent's" knife, with a nice thin blade profile. It's pretty slim overall, and lightest of the group. I used to think the edges were too sharp (handle, not blade

) and I don't care for the plain looking clip, and the fact that it is tip down is a mark against. Still a great little knife. Rating: 8/10
Skirmish: Huge! Looks awesome, and feels great in the hand. If you like big, this is it. there is a lot of material behind the edge, so it's not going to slice your tomatoes as thin as the Buck/Mayo. Still, a pretty good slicer. Only thing I don't care for is the tip-down configuration of the clip. My favorite of the three. 9/10
ATR: Awkward. Ugly. Well designed, and great execution, I just don't care for the asthetics. The lock is weird, although dependable. Now, it is tip-up, which I like, and the clip is a very cool design, (I'd put it on the Skirmish, and be very happy) but there is just too much handle, for the blade length. 7/10
CUDA Dominator: Okay, I know you didn't mention this one, but I thought you should consider it, as it is very similar in atributes as the others. Great blade shape, perfect ergos in the handle, Way cool ROBO mechanism. Again, this one is tip-down, the only negative. I love mine, and would have a hard time choosing between it and a Skirmish for EDC. 9/10
Sebenza: If I could afford this, I wouldn't need any of the others. 10/10
DD