League sucks right now because Riot is entirely overhauling the base systems in the game. We're in an awkward adolescent transition phase right now. Which is why Marksmen were so overbearing for the longest time, they're the only ones really performing at Riot's new standard - Juggernauts were brought to that point but were toned back because~~ they're melee~~ it was too much for other types of champs that were not updated.
Juggernaut update, Marksmen update, Mage update, and probably Assassin or Diving Fighter update coming up soon. The new masteries were a huge power creep too. League is never going to be the same game it once was, and the new design direction seems heavily "less League, more DotA". Before, the difference between champions was heavily nuanced - with multiple champions being able to fulfill the same function in just an every so slightly different way, where you could really substitute similar champions in a particular team comp to get the same result. Now, everyone needs to have their own niche.
Now we're heading into a relatively super-specialized game, where not only champions have to have their own unique niche but items do as well - but they must exceed exceptionally well in that one purpose, which changes the landscape dramatically.