Eh, subjective. LoL's bold colours and strong outlines make actually playing it a lot easier on the eyes.
In terms of what we consider "better graphics" in the world today, Dota 2 has "better graphics".
I'm not saying I'd rather be playing Dota 2, I wouldn't - it's a complete clusterfuck.
But the graphics in it are superior to that of LoL.
If you want to say it's subjective then I'll claim that Tetris has the best fucking graphics ever made cause the bold colours and strong outlines makes it oh so much more comfortable to play.