I had to be away from Malware Tips awhile recently. But before I was gone, the last thing I was hearing here about ZAM was that they had dropped the multiple engines and that the quality of the product was vastly down. If that has reversed, I would be glad to hear it, because I have a ZAM license.
I didn't know that, I haven't used Zemana for a while. Good to know.
Does HitmanPro.Alert indeed now include HitmanPro as a realtime scanner and not just an on-demand scanner?
My 2c: I don't run any companion AV in my PC, and I don't think they are really necessary. But if I did, why would I choose a real time scanner? One Antivirus isn't good enough? A real time scanner... with Avira engine?

Get Avira Antivirus instead!
I think a good companion AV has to have features your main AV doesn't. It should specialise in things your main AV is not is not really focused on. That's why I mentioned 0-day protection, but it could be anti-exploit, anti-ramsomware or anything. When I asked about this before, I was actually curious to see if someone tested it and found anything interesting, but if the most important thing is a real time scanner, then it's not worth my time.