agree. mwb is very heavy on system resources. i use zemana which is lighter, easier to use, and effective!Using more than one 2nd opinion scanner is a good practice.
Personally I would suggest HitmanPro and Zemana Anti-Malware.
One I would not suggest is Malwarebytes - is not as good as it was before.
Sounds like you have a pretty good idea on a few to try,They are all capable of detecting something the other has missed as they all used different engines.
Malwarebytes is great at finding PUPs and types of malware that slip past traditional antivirus
Hitman Pro uses Bitdefender and Kaspersky engines and can detect PUPs pretty quickly
Zemana is similar to Hitman Pro but uses more engines and can also remove unwanted browser settings and toolbars, proxy settings, etc.
Dr Web uses their own engine it's great for removing persistent threats that can remain after multiple scans.
Emsisoft uses Bitdefender and their own engine for removing PUPs and bad registry keys. One of the fastest scans IMO.
eScan uses Bitdefender as well but I don't use it personally.
agreeNPE is the best