Look at the finish and the size. Matte and textured tiles grip better than shiny, polished ones, and small tiles grip best: every grout line gives your feet something to hold. That's why mosaics are the classic shower floor. Makers rate their floor tiles for slip, and we'll point you to the ones made for wet floors.
Big panels, mosaics or microcement in the shower?
Big panels for the walls, mosaics for the floor, or microcement for both. Large-format porcelain panels cover a shower wall with almost no grout, so there's very little to scrub. They're big and heavy, though, so the wall has to be flat and the installer experienced. Microcement goes one step further: walls and floor in one sealed surface, with no joints at all.
Mosaics belong on the shower floor, where small pieces follow the slope to the drain. And if you want color, look at glazed ceramic, from classic subway tile to handmade looks with a little wave in the glaze.