See, I have a lot of dice sets. I have way more than I need, and I'm a little compulsive about wanting more sometimes. And I mostly use them all. I do have a specific d20 that I use as my d20 of choice, though. I don't have a picture of it handy, but it was a stand-alone d20 that I picked up on a whim at a gaming store a few years ago. It's not "correct"--i.e., the distribution of numbers on the faces isn't random, but of course the rolling of the dice is random enough, so who cares? The die seems to be kinda swingy; I get really high numbers or really low numbers frequently, and not so much the middle ranges. At least it feels that way, and some other guys in my group have commented on that as well.
Other than that, I do aspire to a few more sets of dice. I kinda like the ones that Q Workshop does, with the themes. Paizo contracted them to do a number of sets of dice that were themed specifically to their first half dozen adventure paths. I'd like to get the Legacy of Fire and the Serpent's Skull dice.
Q Workshop also has Call of Cthulhu dice, and man, those are the ones I want. They're a little on the pricey side, so every time I think I might buy some, I get turned off, but one of these days, I'll either get over my psychological hurdle, or find them on sale, or something.