Thank you for sharing this feedback and the suggestion, I know ive seen the "Best Win" triggers confuse a few people in the past as well so I'd be curious to get more opinions on this thread
I will say that the Best Win mechanic is a simple yet effective way to add a long term goal to the game for those players that are goal oriented people, I could see myself replaying the same map dozens of times just to beat it at the highest difficulty I can play at.
Kind of did the same thing with C&C Generals, I played that game for years because I just wanted to beat every single map on the hardest difficulty, which takes a lot longer than just playing on every map.
In that it also adds a ton of replayability to the game for those of us who are goal oriented gamers because all we need is more maps (once you've fleshed out all you want to regarding races, balancing, content, etc).
Actually on that, if you wanted to expand the concept of Best Win you could add a mechanic to include races/factions, encouraging players to beat every map as each of faction of Tec, Advent, and Vasari.