I would say that XPanel is great for instant signup mass free webhosting like geocities, but for anything other than that it just doesn't hold up.
cPanel is vastly superior and is a full webhosting control panel. XPanel was never intended to be that so the comparison is unfair.
Now if you would like to compare the UI of two hosting setups side by side. One using something like ClientExec or iPanel (a billing system) with cPanel and then XPanel's own signup system and control system that might be a bit more fair.