Q&A

Poured rubber looks amazing, you can get lots of different colours and a high gloss finish-White rubber looks particularly good and once sealed is easy to keep clean

I agree - poured rubber is great - but v. expensive & not sure about using on a top floor logistics wise. Otherwise amtico have some beautifully reflective flooring in all sorts of crazy designs - plus my favourite - white glitter!

On trend finishes are seamless & polished; rubber, concrete, resin, all could be used to give a highly reflective finish, & can have added ingredients like glitter or sparkle if that floats your boat. But, the cost implications of such materials are high, & the build type / construction plays a part as if you haven't got a rigid substrate. ie. floor underneath your top finish, it is likely to crack, especially resin or concrete.
Check if the flooring is a suspended timer floor with joists etc, or other more stable type.
"my interior stylist' is right, Amtico do a fab reflective glitter type, I've used the red and the white and it looks relatively seamless if no strips are used. Will cost you circa £50 permsq fitted, though you can do it yourself, I have.
Or you could use highly polished stone tiles, again making sure flooring underneath is rigid, and then overlaying a good thickness plywood as a base - just make sure you've finished all your electrics/ plumbing under the floor first!

If the floor is smooth you can think of using Le Mark's self-adhesive vinyl flooring. They do few types of them, some are reflective and available in a vast range of colours. These can be mounted permanently and with really little effort; look stunning and for the price around £170 for 50 meters roll it's an interesting option.

highly polished floor tiles would look nice,you could use it in typical 50's diner way and do the black and white alternate tiles. Think this would be particularly effective in the kitchen.