Difference btw is porcelain is much more stronger material than ceramic. My preference would be more toward the porcelain especially on floors.

you can either go for darker grey tiles or a beige. It all depends on how grey your wall tiles are and if they have any underlying colours - are they are purple or green grey etc etc. How does the ventilator affect the look. Do you have a photo?

I am assuming you haven't finalised your wall colours and colours of any other fixed elements. In case you have finalised your color scheme you would need to see which of these colours blend well or complement with that scheme. Assuming none of this info is available, then you could look at the neutrals which go with all colours. The white tile and the 2 colours at the end would be preferable. If you want color on the floor as well as drama, you can choose from the 2nd options from both sides or even the 1st from left.

antislip and easy maintainance tiles for exterior is the key. choose any shade, colour, size. must not have deep textures as that's gonna be tough later in use. do consider slope and drainage appropriately as terrace may lead to water proofing issues in future. make sure skirting is everywhere and corners with top part of the balcony wall is tiled properly. thanks shradha shah beescheese design