I don't think there is any reason to bash either company.
SSC puts out some amazing pieces. They look amazing, and when they are right on they have amazing paint and fabric apps. Now are there some stinkers? Hell yeah, all you have to do is look in the Spiderwoman thread to see how bad SSC can be. However, for every one of those there are 20 others with simple run of the mill QC issues, and another 10 that have pieces that look absolutely AMAZING! Do they have some issues with creativity, yes, but they put out a HUGE number of statues, and that is going to stretch you creatively.
XM appears to have an amazing QC department, excellent paint apps, amazing packaging, and they seem to listen to the input from the fans that are going to be buying the statues to the point that they add certain extras based on customer input. However, they have only put out 500 statues so far, and it is hard to say how all of the above might change if they start to get bigger. The bigger and more popular you get the more things fall through the cracks. I will say that I love the look of the Iron Mark VII proto they have molded, and I would love to see it painted. If I was going to get one XM statue I think that would be the one.
Honestly, I don't see the point of hammering either company. They both put out quality product. One just costs double is all, but many would say you are paying for the quality, and for a more rare statue.