The desire to win has always been a factor. After all, ASL
is an adversarial endeavour. That said, I doubt many feel satisfied winning (or losing) a scenario due to a single event generated either by dice or an OBA Draw Pile. So the desire for a "balanced" or "competitive" scenario is understandable. Granted some, especially HASL players with a greater interest in a kind of historical role playing, are less concerned with balance than historical "accuracy." But I think most want to play a scenario in which both sides have a reasonable chance for victory.
It's no surprise that players with less free time have become more discriminating, both in their tastes and in how they assess the play-worthiness of a scenario. Some will gravitate toward a particular theatre, period, or nationality. Others avoid scenarios with certain VC, overlays, optional rules, and so forth.
IMO the "best" scenarios are those that come down to the last turn, where they could easily go either way. Judging which are the best is subjective, as two people can play the same scenario and come away with divergent views on its relative balance, or its replay and entertainment value. However, certain scenarios seem to deliver the goods more than others do, which is why they tend to get the most play. If you can only manage a dozen scenarios in a year, then selecting from the best-of catalogue makes a lot of sense. Others nevertheless buck this trend and try to explore new territory whenever possible.
In other words, like everything ASL, it depends.