I chose bumpy white tiles, the cheapest versions available, in the large wetroom at the last house. The Disabled Facilities Grant paid for two of the walls to be tiles because they'd get wet from the shower, but I had to pay for the other two—hence the price decision! The room was originally built as a single bedroom, so it was larger than the average bathroom.
I asked the tiler why he'd recommended picking glossy tiles with a slightly undulating surface, and he said that flat ones can easily drive "noticing" people a bit mad. A tiny, tiny variation in the level of a single tile, which wouldn't ordinarily even be visible, can reflect light differently to the tiles around it; there's also the fact that there's quite a lot of direct reflection from gloss tiles, which can make the light in the room seem harsh. Hence the development of the bumpy tile, which breaks up the reflections and diffuses the light nicely.
Despite their cheapness, I'd definitely pick them again. My current wet room is tiled in a shiny buttercream colour, which shows every tiny splash and mark because of the very uniform surface and the reflections. I'd like to re-do it eventually in that lovely clean white.
