Gotta hand it to Riot on this one, since the release of the new honour system I've seen a massive decrease in toxicity.
I'll admit I was skeptical at first, but I've even found myself being less toxic in games due to hunting for those delicious honours. I've found myself tilting less, and getting an honour at the end of the game actually feels good now, like someone actually noticed what you did. I haven't even received any rewards or anything from the new system but it's making me fall back in love with LoL, with the lack of toxicity in the community. I'd say I've probably had less than 1/10 of the old level of toxic people and flamers, and you actually form an (albeit temporary) relationship with your team mates.
This is a great new update in my opinion, and I just wanted to say thanks!