Well, Katarina is useless against teams with hard CC so I never get to pick her that much, but I loved her before the rework. Her kit was unique, and while the current one is nice as well, I miss the old Kat.
The karma rework was pretty useless. It seemed cool and powerful at first but after a few games with it, I didn't like it at all. maybe it's just not my type of champ
I despise most of the adc reworks. Not because they are bad or anything. Take Graves for example, before he was easily manageable...now every time I walk up to him whether I'm a top laner or a fellow adc, I get blown to smithereens. He just not an Adc anymore really.
I would say I didn't liked what they did to the reworked Warwick and Zilean. I used to play Zilean a lot before he was reworked because of how you can bully the enemy with your bombs, but now I only use the bombs for farming minions. I also liked playing Warwick before, the reworked Warwick is awesome I know, but I really don't like what they did to his ult. I miss enemies tons of times with this annoying ult now.