That's a high standard you're aiming for. I don't know that I'd even call it "competitive". MSE is light, and easy. Those are pretty much the only reasons to run it near as I can tell. The big question is "Is that better than running nothing at all?".
I'd be interested in hearing if anyone here has had MSE protect them from a virus. I don't think I've ever heard anyone say that. Most people with a clue don't get viruses anyway, so running the best A/V, or nothing at all doesn't make a bit of difference. The best question is "What A/V best protects people that don't have a clue?".
I used to use Avira free, but the adware's gotten out of control. I switched my mother to Ubuntu largely because of that. If she were running Windows, I wonder what the best A/V would be? Best is defined as easy, fairly light, and effective.