I love the large format white tile!

The faux marble would clash with the existing floor tile as well, but mainly I just like the large white tiles :)

I could never live with that left one. Too busy. But that's just me. The right one is kind of pretty. And that's a lovely shower.

Plain white

Plain white for sure (that's a beautiful shower!). You have to imagine an entire shower with either one of those "marbles." It will be very busy and not relaxing at all, IMO.

Plain white is lovely, but if you do want marble, for sure the less busy one on the right. As long as the veining in that marble matches the floor color.

love the tile on the right.... i just did my master with similar porcelain 'marble' tile. will try to post pic.

it has a soft look -- really is not busy ...though it may appear like it is...

I love your shower! I would stay with the white tile because of the floor. Otherwise, I have no problem with busy marble. I am especially fond of large format tiles.

The first photo is an inspiration picture, it appears. The actual bathroom is probably the room where the 2 samples are sitting. The small white tiles on the right looks like what the OP is working with at this time.

I like the one on the right. It is similar to what I did my shower in. I like @pat's shower picture above. I did a dark floor and shower pan with my porcelain marble, where @pat did porcelain marble throughout. both work, just depends on your vision for the room. My room would have higher contrast.

The sample on the left could be beautiful too. I would think that you would need to balance the heaviness of the boldness somehow, but it surely could be done, and well executed.

Pat's image is very light and airy. My bathroom has walnut vanity, and casework and doors, along with the light paint and marble look alike tile. I have a dark heavily varagate floor to go with the subtle shower tile. I do have real marble counter top. My walls are similar to Pat's, might be a little lighter.

tile with walnut:

This is my shower pan and the tile for the floor that is darker and a different fake stone look. I like it a lot, but the tile saleswoman was taken back with my mock-up choices. LOL. I could have gone dark gray with the shower pan but went light to hide water mark possibility.

Picture of the floor tile. kind of a blue with greens and browns:

here is the tile before the doors arrived. I was using a shower curtain:

My bathroom is much more contrasting than Pat's, yet we both used the subtle marble porcelain tiles. Though you can't see the tile in this pic, it is similar enough to the countertop that I think this pic represents a good description of the components and how I tried to balance the heavy contrast.

Personally, I prefer the plain white, or a different marble tile with less brown in it and less contrast, but that's just me. Lots of people like marble with lots of movement these days.

I'd do white. I'm always bothered by the repeats in faux marble. But if you choose one, they are both really pretty. One is more exciting, and the other is soothing. Maybe it depends on what time of day you take a shower?

White. It will fit in better with your floor and it is timeless.

@rahmiel The white tile I have found is from Tile Castle Ceramics. It is selling at HD Contractor supply for $0.93 a square foot. They are doing an additional 15% off that price until Oct 1, 2017.