With yellow currently unavailable, I think my next choice would be red. Now that comes with a lot of "if's". There are "reds" that range from hot pink to burgundy, and I'm not a fan of most. For example, for years Chevrolet has offered both "Torch Red" and "Victory Red", plus more recently a "Crystal Red Tintcoat" that are all legitimate red colors. But there is a distinct difference.
See the color chart at the link.
"Torch Red" is a pure red, but with less saturation than "Victory Red", and in the light it appears less "dense". (Forgive me using some TV terminology here, but I get to deal with color-matching cameras in my work) Victory is a richer red than Torch, and I suspect it has a dollop of blue in the pigment mix to bring up that "blood red" color of traditional Italian racing colors - Rosso Corsa. It's what you commonly find on a Ferrari or an Alfa. As such it assumes a much deeper gloss when highly polished.
The same thing happens to blues, those of a darker shade appearing generally richer than lighter, but yellow can be an exception, where "Velocity Yellow", popular a few years ago in Chevy's racing stable, assumes a "school bus yellow" cast, particularly alongside "Rally Yellow", seen more recently in Transformer movies - notably on the Camaro, "Bumblebee". While neither shows off the labor spent on polish and waxing, the sunnier shade, to me,
seems to be "cleaner".
If you're looking for a color match, blue is a whole lot easier to get right than red, but for that reason you have a lot more blue shades to choose from on the color wheel. Green can range from British Racing Green to John Deere - and still appear to be a difference in lighting. Beware - it's also a tough match; as Kermit says, it's not easy being green.
I wouldn't have believed it, but even gray can be a tough match. I once had a business partner who was an artist, from whom I learned there are dozens of colors between warm and cool grays. Well, I call the warm gray "almost tan", and the cool gray "sorta blue", but what do I know? Our offices had floor to ceiling windows down one side looking into a patio - and she insisted on a gray color scheme with a dark "money" green carpet. It took three shades of gray to LOOK like they matched, thanks to the lighting conditions. She nearly drove our painters crazy, repainting everything two or three times. I had them leave my office a nice buckskin tan, thank you.