I love both patterns, but I think stacked rectangular tile looks more distinctly modern.

I prefer subway. I think both are modern and I agree the stacked is more modern but for me the stacked seems too sterile. See pic of job just finished.

I love the look of stacked tile as well. For me, it provides a cleaner more modern look. We laid them horizontally in our bath/shower area. I've also seen it stacked vertically. If you have a larger bathroom, I think stacking vertically could also be a great option.

I was contemplating horizontal on the floor and vertical in the shower, but our bathroom is not huge (not tiny either).

What size are the wall tiles you are planning? Classic subway tiles are 3x6", but you can get something more modern looking that is 2"x8". or a 3" x 10". etc. basically longer, skinnier rectangles. That way, whether you stack them or lay them in a brick pattern, you get a more modern aesthetic.

The tiles are 8 x 10 (for the floor).