What I prefer in League over dota:

- Easier access to defensive choices
- Inclusion of summoner spells, runes, and the ability to recall for easier defensive/offensive choices
- More forgiving laning with lack of gold loss on death
- Lack of tower and creep denying
- Nuke-heavy mages scale into lategame
- inhibs will respawn, making it not next to impossible to win a game when racks go down
- greater emphasis on jungle-based objectives i.e. blue, dragon, baron
- slower, more methodical style*

What I prefer in Dota2 over League:

- item diversity allows for a wide array of playstyles
- supports play an extremely powerful role in this game, compared relatively to lol
- greater lane diversity
- highly unique and individual character designs and playstyles
- inclusion of a courier and ability to buy TP scrolls for map presence
- weaker towers allow for early aggressive plays
- ward limits and lack of clairvoyance to allow for earlier aggression
- faster, more aggressive style*

And probably a bunch of things I've forgotten. They're both great games in their own right and I see no reason why playing one should preclude you from playing the other.