League is more simple than Dota 2 (champion selection wise and the mechanics of the game)
League of Legends is a more of a casual game compared to Dota in my honest opinion. You'll find a lot more trolls on League of Legends than Dota 2 and a LOT of hate if you decide to go into ranked games and die a few times.
The amount of changes League of Legends has done (lore wise and map) changes the look/feel of the game dramatically (from a cartoony looking game and pretty unique MOBA into a Dota 2 like clone) while Dota 2 has stayed the same, keeping to it's colour scheme and beautiful graphics. (not a fan of the League of Legends lore change & map style at all but Dota2 players might be interested)
If you can deal with the hate from the terrible League of Legends community and more easy to learn gameplay, League of Legends would be fantastic but if you're looking for more of a challenge and a beautiful looking game with updates from Valve themself then Dota 2 is for you
(Experience of League & Dota2)