I recently tested Malwarebytes pro on my gaming machine and it had an incredibly low background impact, especially CPU. It did have an issue that it wouldn’t stay registered in Windows Security Center. I haven’t tested Avira. Also, last time I checked Malwarebytes had a decent privacy policy and their browser extension is one of the more privacy friendly.
In terms of detection ratio and FP control, I'd recommend you to use Avira. You may be interested in F-secure, which uses Avira Engine plus their own cloud-based engine plus lightweight behavior blocker, DeepGuard.