Personally, I prefer League of Legends because it is much more simple and it has ARAM. Also, the tutorial is slightly more straight forward. You learn the basics on Howling Abyss then you play a game of Summoner's Rift with bots, where you are taught a little bit about everything. There's no "Play this 10 times with 10 different champions" to unlock stuff. It's a shame the bots don't know how to ward or jungle, but I am not sure if DotA bots know how to do that either, the few DotA games I played, I didn't see any jungling. In both games, if someone starts snowballing, there isn't much you can do. That's inherent everywhere. I feel it is slightly easier in LoL because you don't lose money when you die (as far as I know). The thing that sealed the deal for me though is the UI. In League of Legends, you have several options, including overall HUD size, map position and map size. In DotA 2, I found none of that. It's an informative HUD but it takes up way too much of my screen.