either game gets so mure exposure and communities are so big that doesnt really matter which you pick. dota 2 has the more in-depth gameplay, so if you're gonna commit and properly learn something then i would suggest dota.
Dota 2 is more complex than LoL but I'd say both are good games in this genre.
Pick the one your friends play and play with them, guaranteed fun.
Gameplay depends on the game dota2 is a bit harder in that regard.
Communities both have their weak points and strong points
we could say both are bad.
Graphics- who the hell cares bout graphics
Both have huge exposure TI tournament for dota with its million dollar prize pools and afaik LoL has similliar tournaments
Bigger Community
LoL, but both games have a shitton of players, so you won't even notice
Better Graphics
Very debatable, i would say if you care about graphics that much go play modded Crysis.
More Mainstream Exposure
LoL but same thing for community applies.
Also, once a certains threashold is reached, mainstream exposure just means having to deal with more and more 12 year olds.
MY VERDICT
Play QL, and if you don't like aiming with your maouse play a proper RTS.
If you want to stick to those two, play Dota2 for deeper gameplay and more importantly the fact that you have all heroes for the start and yu're never required to spend money.