This is a very serious philisophical question. For the purposes of the question, let's pretend that both came out at the same time, and had these qualities:
GURPS online was a VERY high-quality text mud along the lines of The Eternal City, but was known only by word of mouth, because SJG\Worlds apart couldn't afford advertising.
D&D online was more MMORPG then MUD, having exceptional graphics but mediocre gameplay. It was also heavily advertised by WotC\Turbine.
Each given about five years to balance out, which one do you think would have more customers?
