Pretty simply, there aren't any other better candidates for mobile, ranged, damage dealers in this game. Granted it's not the optimal group PvE setup, but it's effective in both PvP and WvW roaming, and open world, for what mentioning that is worth.

Besides that, I've leveled and put numerous hours into every class. The ones I have stuck with the most are Ranger, Engineer, Mesmer, and Warrior, with Rev and Necro for "loot tagging."