My personal opinion is that Kaspersky is the best. Don't even feel that its there.
Bitdefender still sux. I tried it one more time today and finally gave up. I have tried it around 5 times just cause of all the great reviews it seems to get from independent test sites, but have not been able to run it for 24 hrs without it giving me problems.
As for Emsisoft Online Armor don't touch it with a barge pole. It wont let you uninstall and when you finally find a way it will mess up your system. Stopped my internet working.
I am currently trying a combination of Kaspersky Internet Multi-Device 2015, Malwarebytes Premium, SpyShelter and Adblock plus. Have tried the combination with Symantec instead of Kaspersky. Both seem to work fine.Oh Yes and have Hitman Pro sitting behind all that with Emsisoft Emergency kit standing by. Haven't faced any slowdown in my system except maybe a bit during boot and shutdown though negligible . But once its up it runs fine.