i think that it would have to differ slightly from the AW heart (favorite) designation because it would be a choice of 1, 2 or 3. But a similar look would be good and in the same place it is currently on the mobile app.
Well, this gets into an idea that has been floating around in my head for a while.
It seems to me, and this may not be the popular view, that the aid to the builder is not as good as it used to be with the advent of timer instants. There have been times when the aid to my builder actually made things less ideal because it dropped the build time to an amount less than the timer I was going to use to instantly upgrade my building.
Picking one favorite instead of a ranking system would eliminate some player control, but I don't know that it would make a huge impact.
If you eliminated the builder and just had culture and main hall, then you could have one favorite and not the other.
For streamlining, I feel like we could even go one step further. I wouldn't mind if the choice option was eliminated altogether and the coding just aided culture first and then Main Hall if all of the culture were exhausted. This may not be to everyone's liking, but for me, I don't really care that much what people aid. I would much prefer half of the clicks be removed when I aid others.