Many things:
Health regeneration (COD Style): Why? Why would you need this? This is horrible for Medics everywhere
Defeating the purpose of something: Medic: Made to heal. We can't have medics if every other class in the game has an item that HEALS THEM!
Escort missions: No. I don't mind them very much, but when you're defending them from guys coming from behind, in groups of four, a new group appears every few seconds, and the thing you're escorting is SLOW AS BALLS, then yes, it gets annoying.
TF2 Trading and why I deny requests now:
>Kill somebody
>Few seconds later I get a trade from them
>"Are you trading that?"
>"IF I WAS USING IT, WHY WOULD I BE TRADING IT?!"
>Cancel trade
Horrid AI: I'm shooting guys up in Sr2, when suddenly- BAM! I get ran over by twenty AI who refuse to exit their vehicles.
Bullet Weight- No
Bullet's that take an hour to reach the target- No
Hardcore Snipers who play nothing but Sniper- I'd rather drown
