They're both very different products. I would say the pumps and fullnes from X-Gels is better initially for sure, but you also need to factor in the increased DOMS and muscle soreness. Massmax XT had a more significant impact on my hunger the first few weeks, and I felt the strength and size increases around the 3-4 week mark.
I would highly suggest trying both products at different times to see which you like best, it's a very difficult comparison. Since they work differently it's hard to compare them and say one is better than the other.