I agree with comegetme about getting samples together in the actual kitchen space. The reason why I prefer the lighter one is the pattern. Even though I really like the pattern in the darker one as a single tile, I think that the floor will end up with too many fairly clear lines running crisscross, or if they're laid in the same direction, the lines will never match. I think it would drive me bonkers. Whereas the marble effect tile has a softer and less linear pattern. But it might not be a problem for you :-)

I wonder whether a darker wood effect tile would work on the floor? Darker wood seems to create a more classy feel whereas the pale wood tiles (which are nice) seem more beachy.

Walls and Floors have these https://www.wallsandfloors.co.uk/white-tiles-white-floor-tiles-15072 https://www.wallsandfloors.co.uk/matt-black-white-floor-tiles-black-floor-tiles-15071

Thanks for the advice everyone. The walls are just plastered at the moment, so I'm thinking to paint them a shade of white first to get a better idea of how the space looks, then decide on some tiles. It's difficult to picture with how it is at the moment! I do like the idea of having white zellige tiles placed vertically, but worried it might look a bit busy if it goes from the countertop to the ceiling.