Short answer: chrome and brushed nickel are the most water-spot-resistant and easiest to maintain. Matte black looks great but shows water spots more visibly and needs more frequent wiping down.
Why finish affects maintenance
Polished finishes show water spots more than brushed ones, since brushed textures hide minor mineral buildup between cleanings. Dark finishes like matte black show spotting more visibly simply due to contrast, not because they're lower quality.
Simple upkeep that actually works
A squeegee used after every shower prevents most spotting regardless of finish. For hard water areas, a weekly wipe with a vinegar-water solution keeps mineral buildup from becoming a permanent haze.