I think the build and share group challenges have done a few things right which could add to the "legitimacy" of Maxis favorites. In particular, I have a great deal of respect for how they have three different tiers of competition, depending on the experience of the builder. I really appreciate how it encourages newer and less experienced builders to continue becoming better. Mind you, they're also dealing with a much smaller pool of builders than the entire gallery, where it is easier to keep track of these things. But I like how it encourages people at different levels, and how transparent the group is about the judging process. They're extremely clear about the fact that the final scores are, in the end, all based to a certain degree on the personal taste of the judges, and there's never any way to take personal bias out of the equation. But if a person wins a competition at a lower level, that same person might be held to a higher standard next time.
Maybe that's impossible to keep track of on the scale of the entire gallery. However, we, as the people who can nominate work in the recommendations thread, might apply a similar standard to our own nominations. For example, if I nominate BryonyRae for her latest build, and she gets favorited, maybe I shouldn't nominate her again unless she really brings it to the next level (because I know she will, some day).
The fundamental point I am trying to make is that I'd love to see people get recognized for improvement, whatever level they start at. I certainly won't claim, though, that I have a perfect answer for that yet.
