My biggest issue with the preseason...
Is the changes to EXP gained on kills. I know they were small, and I know that most people didn't even notice, but they are infuriating to deal with. If you get killed in lane, you're already losing out on CS and exp, but now it's even more exp granted for kills, making it really common to see people with 2-4 levels higher than their lane opponent. It turns lanes into impiossible stat checks because that big of a level difference is massive. If someone's fed, they already have superior itemization, and literally NO ONE complained that kills didn't give enough exp. It's ridiculous.
Worse, it's made junglers even more feast or famine, because if they get kills, they'll end up 2-3 levels higher than the enemy jungler who doesn't have them, and subsequently be able to farm more quickly and safely because of a level advantage, and snowball even harder. But if you get behind in the jungle, or even if you just focus on farm instead of kills, you end up losing badly to the other jungler.
And as a support main, I can safely say that the level disparity between supports and everyone else has gotten way worse. It could just be because they'res more exp in kills (which supports don't get in the ideal circumstance) but I've seriously been level 12 when the enemy team has level 18s. I'm sure part of it is the removal of the ambient exp mastery, but still, the level disparity is terrible. It makes me never want to support, because I end up so ridiculously weak that I just blow up because I'm underleveled (unless of course I'm fed).
No one ever talks about this, but the exp differences are just crazy. Riot posted that the reason that they keep removing ambient stat passives is because they don't like this game to just be a stat check, instead of a dynamic battle. Well, EXP difference turn it into a stat check because it's almost impossible to kill someone 2 levels higher than you if they're even remotely competant. Please, for the love of all thats holy,, remove the EXP gain increases on kills and bring back the ambient EXP passive.