I mean, trendiness isn't really the way to decide this -- looking on this site, I can see brass, black, nickel, etc. I'd match the fixtures in the tub.

All old cast iron tubs have painted feet, it was what was available at the time. Chrome seems way too contemporary. When I’ve had tubs I’ve painted the outside and accent color and the feet gloss white to match the rim and interior. Just personal taste.

You have a lot of finishes already in the space so at most pick one of those for the feet but I would just do a good metal paint in white gloss

White might be the safest, but you can easily change if it makes the white tub look yellowed or grey.