Had multiple Av-Solutions over the last 15 years, ESET is by far the smoothest I've ever had. Pretty easygoing on the System, doesn't bother me with pop-ups very other second, etc...
You should not rely too much on the AV Test Labs, since they rarely test a real-life Scenario, sure, ESET has it's rough corners and problems sometimes, but not more than most Software that works on this large Scale
Haven't spent too much Time with Bitdefender, since It's not really well known in my Area, compared to other Av's.
Running two AV's at the same Time isn't a good Idea, since they often conflict with each other, eg. Av1 recognizes AV2 as a Virus and wants to block it, while Av2 deals with the block attempt as an attack and tries to block av1, etc...
I think I've read somewhere that you can use components of two different Av's together, but I'm really not sure how this works, so no promises here