Gamersgate is the other distributor worth considering. While not quite as big, I think it's still big enough to get you the word of mouth thing going on the nets.
In any case, if you want exposure, the distributor is generally not the way to go as there are many other more far reaching methods out there. I for instance don't really click into every single game on online digital distributors, especially indie games. I for one, and I suspect I'm not alone in this, take sites like RPS that often have a similar taste and standards in games to hold much more sway than the page offered on the distributor's page.