They call the budding genre "MOBA" Multiplayer Online Battle Arena.
Played HoN a bit, prefer LoL, mainly because I kinda suck and in LoL when you suck you get paired with and against other people who suck automatically by the matchmaker. In HON you have to join a game in a battlenet style room, and there even in the games marked as "noobs only" you will get treated like utter excrement if you do not already know basically everything about the game.
HoN is more like dota, if you played the original mod... it's basically dota 2.0.
LoL is kinda an evolution, more like DOTAlite but with more fun and less encyclopedic knowledge of items and champions needed..
HON is the PS3, LoL is the Wii.
If you are an old DOTA player, know what you are doing and are looking for a high competetion game, go HoN.
If you are new to the genre and looking to cut your teeth, go LoL till you get good, then move to HoN for higher level play (never admit you played LoL, they will treat you like a leper).
If you are just looking for fun and to get your toes wet with the new genre, go LoL.
LoL's community is mean, evil, and unforgiving of mistakes too, that is just the way it is in this line of gaming, but they are 10x nicer to newcomers then HoN or DOTA's existing communities.