Just my opinion
The XM base blows away TH's simple base... XM's is more detailed and looks more realistic where TH's looks more simple and comic book-like. In the end, it really depends on your preference, do you like realistic or the more animated look? Although I like both style costumes I do believe it will play a part in some collector's opinions...
I do prefer the hovering pose vs the standing pose... to me it's a bit more Iconic... I will say that I'm tired of the same cape style of it blowing to one side, I would have preferred if XM kept the cape behind him instead of blowing off to the side.
Based on what each company was going for, I think they both look great... It will be nice once TH replaces their messed up Superman statues... I'm guessing another 6-8 months