I ended up with my current IDE font (Fira Code) winning. Could be that I just prefer this font or I'd accidentally gone with a familiar option.
My main reason for liking both is ligatures support, which the website failed to show off.
One property that might make that list is whitespace between lines. This one is misleading though since it can be adjusted when rendering (in some IDEs) with leading.
Same for me, even the same font as for you, Fira. I just find it very clear and simple and it supports a great set of ligatures. A lot of other fonts I didn't like at all. So maybe I subconciously chose this, but I feel it's also just a reflection of my demands for a coding font.
But I agree that it might be good to try it anonymized -- I was very impressed by the eventual winner when I saw it early on, and I remembered its name. I could feel myself slightly favoring it in later matches. Then again, maybe that's a reasonable part of the process -- this isn't really an objective judgement to be making in the first place.
Single elimination also isn't likely to produce the "one true" result, unless the initial pairings were very carefully chosen to partition the design space. (I think they were random, so the result is somewhat arbitrary.) Still a fun little exercise, though.
I ended up picking Noto Sans Mono by a very slim margin over Fira Code. Interesting...