Having used the Slimarmor and the Diztronic TPU, I just recently moved over to the Tech 21 D3O case from Tmobile and I'm loving it.
With the slimarmor I felt it being a bit bulky as well as pretty slick at times. With the diztronic, I didnt feel as if there was enough protection if I were to ever drop the phone.
Looking at the videos of drop tests online for the d3o material, I was sold. The fit is snug, the only bulk added is on the edges where the d3o material is. The textured tpu is nice to hold and doesn't feel slippery, plus I feel much more confident in the event if it were to ever drop on the corners/edges of the phone. For the front face drops, hopefully the Glass M protector I have will take the impact.
Very satisfied with the Tech 21 case and would recommend to anyone looking for slim and protective. They have them in the Tmobile stores so you can definitely try it out first before you buy!