50 games really isn't very much in these types of games.
In my opinion dota 2 is has a higher skill ceiling than LoL (not an expert, few hundred games of dota and around 1.5k lol but haven't played other in nearly a year) but that is not to say top league players are not good (and who cares, watch/play whatever you enjoy).
On topic: for popularity, obviously league is number one. For personal favourite, I enjoy sc2 the most but love watching TI and LCS for dota/lol.