Maybe things have changed since all of the other MOBAs came out, but back when DotA was THE thing to play, no one would ever let you try to learn how to play. Every game was "no noobs" and would auto-boot you if you didn't have the map downloaded already. Then, when you played a "noob" game, there was usually a good player in there just trying to boost his ego. I'm not saying LoL doesn't have that in the community, but look at every online game and you'll see those parts of it.
OT: I've played all of them and I would say that I did prefer DotA, but I like LoL and HoN a lot more now that I've been playing them. I'd have to give my favor to LoL out of the two though, but probably because a lot of my friends play it and that makes any game more fun. I love the characters in LoL, there are very few that I don't enjoy playing and they are always getting new updates. I only wish you could deny creeps.