I prefer Matte on floors.

the slip factor is primary, but keeping a polished floor clean and 'polished' is important too.

You can even combine matte floors with polished matching tiles in a shower. Looks fine!

If you selections and style will be more formal and traditional select the glossy floor. If the bath will be less formal then select the non glossy floor tile.

For my master bath I used the same marble-look porcelain tile for the whole bathroom, but matte on floors and polished on shower walls. Guests might not realize the floors are slick and then slip when coming out of the shower/tub.

I did use a polished tile in a powder room, knowing that there would be no water on the floors.