I've been playing LoL for three years, and I can honestly say. The game is not as fun as it was, the game has turned from "Strategical champion picks and itemization" to "Whats to most broken thing at the moment, that I can abuse before it gets patched?"
Examples of items that were abused until a nerf are:
Liandrys - Used to give more health, and passive was stronger. Could be the ONLY damage item on Elise, and she'd still be a huge damage threat.
Blade of the ruined king - Used to deal magic damage, instead of physical. Higher stats, for a rather cheap cost. Was meant to be an early item for carries, but instead every bruiser got it, even the ones that don't rely of auto attacks, and still used the item to its full ability.
Spirit of the elder lizard - Much high stats, used to be built on any Jungler or top lane, for its unique utility combined with its passive. This item has been nerfed almost every patch since Preseason ended. It's still currently being abused on Ezreal, for its CDR, sustain and true damage.
Black Cleaver - Everything stacked. Anything that had high base physical damage, could get 5 of these and have max damage output(That couldn't be countered), as well as massive health and full CDR.
Examples of champions that were abused until a nerf are:
Ability Power Tryndermere - Broke his game mechanics, becoming impossible to zone early game. This was bad, because Tryndermere is designed to have that poor early farm, as any Melee Carry is. By building ap, he could coast through early game, gank efficiently and not die in teamfights, while still have a consistent damage output. At least with AD Trynd, you get a chance to stop all this, but with AP you had no choice.
Taric - Everything you could ever want from your support, Taric had. 1.5 Stun? Burst of heal? Aura's? AD buff? All of it, he had. but thats just in his spells. Not only does this benefit his ADC, it all comes back to him too. With itemazing nothing but Aura and other utility items, he became a Tanky Support like no other. Taric could grant everything needed to win a teamfight, and had enough zoning potential for laning, and protection from ganks. Taric was the perfect support, reaching the highest win % before he got a nerf.
Eve - Max health % AOE ultimate at the same range as Lux's E. Lucent singularity. It was impossiable to miss, combined with the old Liandry's and Eve could use her full kit, to decimate any high priority target in a blink, gaining a reset on her speed boost, she wouldn't even get any punishment for it, even if she had some struggle with the target, the sheild and the cleanse from her boost kept her safe. Her huge range on her passive, made her effective at using this one trick every time. Damage too high, range too long, sheild too big, cooldown too short and the slow too hard. Some things had to go, and now Eve's ult deals current health % making it impossible to sneak up to a low health champion and abuse the huge range of the ultimate to kill them. Eve now has to fight in a more risky position if she wants to have the same outcome before her nerf.
Hey, I'm not saying the game was never liked this, I remember season one. Ap Janna was huge for a while. But things like this didn't happen so often, But when I join a game. I don't want to pick someone because it's "OP" and I have to abuse it. No, I want to pick someone because I'm great at that character. and in Season 3 League of Legends, that opportunity is very rare. Because you will be stuck with 9 other people in a game, who just want pick the flavors of the month. Still a fun game though, alot more fun than other MOBA's or any other online game.