I'm not a huge fan of KFC. As Sah said, crazy salty and greasy as hell. The buns are like polystyrene too and the fries are limp and tasteless. I certainly don't regard it as a treat, quite the opposite. It's like a last ditch choice for me.
Nando's is hugely overrated too IMO. I often find the chicken dry and the side dishes poorly cooked. It's fine, and certainly a step up from the beige slop KFC churn out, but it's just nothing to write home about.
Greggs can get to fuck too. Questionable lukewarm mush wrapped in undercooked greasy pastry. Mmm, delicious. :/
MaccyD's doesn't particularly stir my beans either, but Burger King is pretty tasty. Really good crispy fries and the burgers are usually decent. Well overpriced though.