ADWcleaner, Malwarebytes, Avast free

After doing some questionable installs (and still doing custom installs), some shady stuff got onto my computer. Avast did a great job blocking registry hacks but didn't find much on the full system scan. Malwarebytes got rid of the PUP that installed the shady crap. And after all was said and done, ADWcleaner polished everything off by finding every last trace of crap left behind by the adware. After that little episode, I can't recommend ADWcleaner enough, on top of everything you already have.

I used a trial for ESET about 2 or 3 years ago and liked it a lot, but I'm too cheap to actually pay for it. I just settle for Malwarebytes and MSE since they're free and get the job done, though if I ever decided to cash up for an AV I would definitely go with ESET, easy to use and not a memory hog.

I have been using Bitdefender, but it's a bit on the costly side, $70 for a year, though if you live in a shared household, you can buy 3 licences for a year for $150 (or 5 for $200) and save some money that way. I really like it, it's quiet in terms of how much it bothers you about stuff, speedy, and I have yet to get a virus while using it. It even has a Game-Mode setting that you can turn on that makes it quiet right down to improve performance. I had been using CA Antivirus before Bitdefender, and I'd say that Bitdefender trumps it in every way. It also has some simple PC clean-up functionalities, like registry clean-up.

Eset Nod 32 here, and if you check NewEgg around Black Friday they will put it up for $5 to cover you each year otherwise they offer enough coupon codes each month that you can pick it up for $12-$20 for 1-3 PC's.

Also never forget people still buy software on disks. You can often find your favorite antivirus on sale at places like Best Buy that have codes in them to renew a subscription. I just picked up a couple of years of ESET for 60% off.