I use MSE atm.

Used to use AVG/Avira/Avast.

Avast was just...weird.
AVG was overrated then and started to feel unreliable.
Avira....I feel they have a good shield/real-time protection system but their virus cleaning system suck balls. <-- Caught a few diff type of virus/worms [ofc not the ordinary ones] and it couldn't get rid of it.

I feel MSE is alright.