Im giving the nudge to the Single Bow Tie. I just got an RCA ANT108, and Im impressed with it. It seems to be fairly well built, nice and tight. And it did pretty well for me but not as well as the single bowtie, but it has rabbit ears for VHF Hi integrated that the Single Bow doesnt, so plus one there. I think your issues with multipath and interence made the RCA's lessor gain an advantage in your situation(not to mention it has rabbit ears for VHF Hi. The MANT510 has a more directional array I think, and even if its not, one side is permanently downwards oriented. I think that is helping you.
I like the 1868 too, even though it doesnt look that way from the list. It the MANT510 and the RCA ANT1500 are tightly packed and I like them all better than the Philips MANT940 and the amped Youtube antenna. Im still working on things, atmospherics are almost certainly skewing my So Far Performance list. I used the Single Bow Tie today, and it didnt do as well, but still pretty good.
Oh, the RCA ANT108, I like it.Surprise #2!
Performance rankings.....based on EV's observations....Rough Guide
DB2 with Channel Master 7777 amp
RCA ANT1500 amped
Classic Single Bow Tie
Winegard SS-3000RCA ANT108 (very similar to the RCA ANT110 and the Philips MANT110 and others)
My First Attempt at the Coat Hanger Antenna, Youtube Video Specifications.... amped
Philips MANT 510
RS 1868 Delta
My First Attempt at the Coat Hanger Antenna, Youtube Video Specifications