Well I've played Dota, Dota 2, LoL and HoN and I would go for Dota 2 because if you apply for a dota 2 key you will get it in less then a month so its basically for free, it requires a lot of higher IQ when it comes to FOG(hill/valley), towers, creeps, teamkill possibility(poison).
Donate is there only for design of hero so you wont find a player with +30 P Attack bonus on start like in LoL.
Minor amount of Leavers and a really nice anti afk system on start of the game.There is not such a big problems with russians like in the old dota. New heroes are getting added from the old Dota. Best way to play it is with friends.