Tiled. And, I'd use a surface membrane like Kerdi on it. This way, there is so much less that can get wet. For a neoangle shower, you probably wouldn't want to use their foam pan, make it out of mud. While you can cut the foam pan to shape, you need to cut it evenly so the outside edge stays at the same thickness or your bottom row of tile won't be aligned. Functionally, it doesn't matter, but you may not like the look. But, at 1/4" per foot, it often isn't much. A mud pan will compensate for an uneven floor - with any preformed pan, you must make sure the floor is leveled before you install it or nothing will line up or drain properly. Have you checked out www.johnbridge.com?