League of Legends was made with complexity/difficulty != fun in mind.
It's easier to master mechanically, but I feel it is all around a much better made game. For one, it actually runs smoothly. This could just be my PC, but super lowest settings and custom config on DotA2 still runs sluggishly, while LoL is very responsive and satisfying to play.
Gameplay-wise, DotA is very cutthroat in that a single hero can go rambo and 1v5 the other team if he gets out of control, while LoL generally allows you to come back if you play smartly with your team. The item shop in DotA is terribly confusing, but I suppose you'll learn it if you play long enough.
The only negative things I can say about LoL is: the leveling system and runes/masteries, while helping new players ramp up to competitive level, seem to take a long time to fill out to get on par with a "normal" player. DotA 2 allows you to jump in straight away on the same level of play and with all heroes available. You have to unlock champions in LoL (it takes a while if you take the free route as most do).
TL;DR - LoL is a polished, simplified, beautiful take on the MOBA genre that DotA popularized. Hardcore DotA fans will call it easy/noob-friendly/etc, but in reality it's just different and in my (biased) opinion, better.