I've played a ton of both, and I vastly prefer League. Yes you actually have to play to unlock things, hard for some people it seems, but the game feels more responsive. I do love all the trolls of comparing league to some game with no depth or skill involved. Both these games require skill to play and be good at. At the end of the day it's personal preference and good luck getting calm explanation from MOBA fans as this community is hugely toxic and defensive of their game of choice.
Edit: Also League has the numbers in terms of following. Idk if that matters to anyone but the vast majority of people play league over DOTA.