I just looked at Dota 2's graphics. They are just brighter and more cartoony.
When I went to take this picture I realized that my resolution was wrong, so I changed it and LoL actually looked a lot better. Although personally I still think it looks more cartoony when compared to Dota 2.
And no I actually haven't played the first Dota. But what I meant was I think the characters are better developed in Dota 2, and maybe it was because of the time put into them. Whether or not the latter is true doesn't change the former, that I like the characters in dota 2 better.
But as bad as it sounds, now that I got the resolution looking better I might actually give LoL a second try. It just looked so horrible with that resolution that it made me look at the rest of the game as bad, hehe