Well, honestly, probably D&D because D&D is by a country mile the most popular Tabletop Game and has been for a long time. The law of very big numbers means you're more likely to find all sorts of non-majority players of D&D.
That said, yes, any given random group of D&D players could just be a bunch of straight cis white dudes, but you still have better luck finding a more diverse group overall by starting with D&D, because you'll have more to choose from.
Whereas a more obscure game may only have one group in your area that plays it.