My personal choice for paint there would be a gloss or semi-gloss oil based enamel. It's durable, easily cleanable, and more water-resistant than latex products. I'd avoid anything textured as it will be hard to clean. If you are motivated enough and have the time, you can also use multiple colors and paint the fake grout lines back in, making it look more like a custom tile job Lotsa detailed work in that but maybe best look you can get out of it on the cheap! If you do paint, scuff-sand wherever it's shiny so the paint will bond, and prime with original Kilz or Zinnser 1-2-3.