TTK feels like it's in a really good spot. I think Hit Reg isn't the best and I definitely notice bullets not registering at times.
The other thing to take into consideration is lag compensation. You're waiting for someone to turn a corner and then they instantly kill you. That's lag comp. On their screen they turn the corner and you're just sitting there staring at them lol. I think games need to stop compensating for people's terrible connections.
Stop using wifi when you're playing shooters people! If possible, I know some people don't have a choice.