I like the YHM skeleton stock. I've also used the ACE skeleton, and it looks nicer, but the YHM handles better for me, and the YHM stock has an external tube that fits over the original buffer tube, which I think is a definite improvement in strength, in a potentially fragile and very critical area.
The ACE, is about 1/2" shorter than the YHM stock, which seems to me to be about the same as a regular A2 full length stock..