Hmmm... I've tried, over the years, to use my chosen barn color. At first, didn't have many options there, but then Purple became very popular!
Personally - she'd look good in any of those colors. I usually prefer a bay NOT to be in pink, but we have a bay mare that wears pink and even though Im now riding her (daughter's mare, she chose pink in 2001), I've continued to use pink on her. I just think of "her color" as being pink (well her name is "Pretty Girl")...
The only reason we had different colors in/at our farm - each of our 3 daughters had their chosen color (s) on top of our barn colors. So often they had red (alternated with blue) or pink or teal (which later switched to lime green)... I got their brush buckets in their colors, brushes, halters, leads, lounge lines, made training martingales, saddle pads (at least for fun), leg wraps, and sheets in the girls' colors. We always knew which horse or pony it was for, too, w/o having to check sizes if they were close, LOL. OR you knew who was riding which horse/pony as that pony wore that daughter's color that day. It was awesome!! Everytime I went to a new area, I had to check out tack stores and find brushes, curry combs and hoof picks in the girls' individual colors to go in their grooming buckets...
You do different colors for each of your horses? What are you doing with the color choices? Brushes, halter, bridle, harness, cart, trailer, sheets/blankets, leg wraps, buckets? Yellow is difficult to get in each of those items... For some reason, even though our barn colors are purple/black/white, I've gotten into the lime - and your bay mare would look good in lime... I seem to be the only one who has voted for lime, too.