It's not so much that one stage is "better" than another. Each has it's own benefits and flaws, it just depends on what factors are most important to you.
For me, I choose the SSA because it is really easy to break down and set up (I can do mine in under 2 min now). However, it is definitely still big and bulky to haul around, at least it's in pieces. I also like that it is low to the ground (like 4 inches high), making it easy to do floorwork. I always have to put some sort of yoga mat down on hardwood / uneven floors, and it does affect the spin mode a bit, and make it slower.
I do not like that my SSA pole can come unspun (on static mode, with version 3.0 -NOT the EZ connect). But then again, I use it mostly on spin, and I use it for parties / events where easy portability is my main concern.
The X-pole's big benefit to me is the locking pole with hex keys, you know that pole isn't going to come apart, (but then again, I have not tried PS EZ-connect to compare). Last time I saw an X-stage get put together, it took about 20 min. While it does have legs pop out past the round stage area, they choose to only use 1/2 of them, and weighted under the base down with sandbags for added stability. They were concerned someone would get hurt during the competition on the extra legs. The spin mode on it was great, and really fast and smooth.
So the big question is, what's most important to you? And I agree with Chem's statement, there are lots of reasons to choose one versus another. The great thing is that there is no wrong answer. =)
*Pole love*