Since it's a pretty split question, i thought i'd make a poll on one of the greatest hubs for blizzard-related things, too.
Heroes of Newerth is a DotA-Clone with updated graphics, matchmaking systems, and such. gameplay is stable, by S2 team.
League of Legends is a DotA-Clone with a cartoony-style graphic, and doesn't carry so many features of dota like HoN, bringing in a number of new features and forgoing some, done by Riot Games, with Pendragon (of Dota v5.x fame) and Pendragon (Of Dota-allstars fame)
Refrain to vote unless you've played both of them and some DotA, please =)