I wouldn't take it too big either, because it should also fit the room and not consist of nothing but cuts. From 60cm upwards it looks stylish to me, especially if you also show a good sense of color. You can partially admire WCs with a lot of stainless steel at small [BAB] parking lots.... yuck or, as mentioned above, in prison. I believe you have to contribute a very homey level of creativity there or you can quickly get it completely wrong, which is why the classic tile style would definitely take precedence for me. Besides, the options with tiles/grout are practically endless.