So which do you find most interesting? If you haven't tried League of Legends, a link to try them out is in my signature. Give it a try, I find myself playing a couple rounds every now and then. I find some older DotA players prefer the older game though. Just some info - LoL is by the creators of DotA.
I am playing DotA on Garena, this game is very nice, I spend some time on LoL but this game is so slow... so choose DotA q-;