Any heavy team based multiplayer community generally ends up being horrible, not just these DoTA clones. I played World in Conflict for a bit, and you'd often have high ranked players in public games screaming profanities at the low ranked players instead of calmly explaining what they're doing wrong (this was a game with no skirmish mode either, so you had no choice but to play online to practice). It's like people completely forget that they used to be an inexperienced newb at one point too. But no, rather than try and help the newbs so they understand what they're doing wrong people seem to go Internet Tough Guy and relentlessly flame them until they quit. Then act surprised when the community is dying months later. I could understand being annoyed if a newb got into an otherwise high-level ladder game, but you get too many cases where people troll low-level public games expecting everyone to be a pro or something.
Anyway, the answer the OPs question I've heard HoN is pretty much DoTA with better graphics, while LoL tried the make things a bit less hardcore and more user-friendly. HoN seems to be more popular in the competitive scene from what I've been seeing, but LoL has the advantage of being free if you don't mind the character limitations of a free account.