Well I had both and the traction is thinner then the symmetry. The traction series for some reason has a large camera cutout and allows dust the back of the case. The symetary case is good but it is thick. So it's up to you, for me I prefer tech 21 cases. Now the Apple store sells the statement series but those have leather or swade on the bottom and those peel off over time.
I had the traction case for about a week and noticed the same thing with the camera opening on the back. Also started to notice some scratches on the back, but to me that wasn't a huge deal. I ended up returning it for an Apple leather case. My wife has the statement series and it did feel a little thicker than the traction. The traction also feels like it had a little better grip on the side, granted I obviously spent a lot more time with the traction case than the statement.