It depend on the Water flow layer, if it do nicely than water will go to Holes else using what tiles will be useless...
Example: Hole is on Left side and water goto right side, than is tile may different?
Also, how heavy you could use when taken bath or washing your Kitchen?

For WetKitchen, you may want to use 1x2, and for toilet maybe 1x1 or 1x2 lol...