Yeah, I play both as well, and it is hard to decide.
I think I end up playing LoL a bit more though, simply due to certain annoying things about Dota. The deny mechanic, for instance.... bloody stupid. Let's shoot my own troops in the back of the head... that'll sure teach the enemy a thing or two! Or the laning.... there's not much action during the laning phase, unlike every other moba I've played. Since spells/skills take up such silly amounts of mana, you cant be poking with them pretty often.... so the laning phase often ends up being just the occaisional trading of basic attacks and not much else. I'm aggressive and impatient, so I'd rather there be more direct fighting between me and my opponent during laning. Not to mention the overly done focus on last hits, and the constant need for supports to buy ten billionty wards for a zillion gold each...
It's still a great game, but those elements always just irritate me a little too much. Granted, LoL definitely has it's flaws, but they never seem to be quite as obnoxious.