Make Kog More than a W Bot
Pre-rework, Kog was an interesting, versatile and high-skillcap champion. Now, he's nothing more than a W bot. You don't even need to be a decent ADC to get a lot of mileage from just standing there like an idiot with W on. You'll die but probably take the enemy team down to half.
As shown by SKT in the IEM finals, even the overbuffed Kog has counters and you can bait out W/split-push/flank etc. but in uncoordinated games, he is too effective for how little skill he requires. If you had a Twitch or Jhin, they could be maybe even better but those players actually need to be skillful to do it or they'll be garbage. Even a bad Kog is useful though and I miss how he was pre-rework.
I'd much rather have a weaker W but more powerful other abilities and skillful expression.
all have so much power allocated in one part of their kit, the rest is sort of meh. Blitzcrank and Kog are especially bad with this problem. Power needs to be siphoned out of certain abilities and spread out for a more balanced kit.