Definitely gloss and the glossier the better. I did the POR15 route on mine and when I was done, it sparkled like a piece of polished onyx; never expected that the old cracked wheel could look that good again. Then it dawned on me that the paint would not stand up to the abuse that a Bakelite wheel could take and it would be a mess in short order. While it was still perfect, I put a Wheelskin cover on it (fits like a glove) and it looks great. However, all that work was for now naught, save for the little parts peeking out at the spokes.
Initially I was bummed, then I remembered that I didn't build this car to impress judges (God knows, the judges would absolutely hate some of my upgrades); I built it for my personal satisfaction. There is a lot of other work inside and under the car I did to satisfy my standards that no one else will ever see. I am happy being the only one to know that the wheel under that leather cover looks like a million bucks. After all is said and done though, I'm glad I added the cover because the Wheelskin bulks the rim up a bit providing a much more comfortable grip.
Joe