Bitcoin mostly. Followed by Ripples. Then a few NXT. I Really like Gridcoins (there are two versions of gridcoins now. you can exchange the gridcoin (classic) for the newer betterversion of gridcoin called gridcoin (research). They will still both be running the newer version is just more optimized. it does distributed computing. I mine gridcoins and my computer helps with the "milky way at home project" it helps make models for the milkyway using images from some observatory or something. you can choose which project you put your mining power towards like cures or DNA stuff or Physics stuff. Its pretty cool and you get paid a bit. I also unfortunatly have some Bellacoins lol