Dish washing soap and water works for me. I clean it often so maybe that is why it works. I rarely have any trouble clean anything.

I often use a vinegar and water solution in the bathroom or my steam cleaner, but if soap scum has built up I like to use Comet Bathroom Cleaner on the tile. It's a spray with citric acid. At one point in time, we had a weekly house cleaner. We supplied the products, and this is what they requested because it works well and isn't full of lots of horrible smelling chemicals.