People definitely use the x-system more. However, as Neil Roberts noted above, the h-system seems to be slightly more popular with older Esperanto speakers, who learned before computers existed or were so popular, and it is considered to be the official alternative.
Joop Eggen mentioned that the h-system looks more pleasing to the eye for non-Esperanto speakers. I think this is definitely true, because it makes it resemble a "natural" language more closely. However I have found that after knowing Esperanto for a long time, the h-system looks annoying to me and the x-system is something I barely notice. I see the x-system much more often so my brain processes it easily, while the h-system is infrequently used, making it jarring and unattractive to me.