Top photo is smoke bottom is silver. Anyone have experience with these colors?

Definitely the darker grout.

I need a tie breaker! Lol

Darker

Just finished my bathroom. Same colouring. Like the smoke Gary. It won't discolour over time.

Carol's comment was the first thing that crossed my mind. Trying to keep the white grout clean would drive you crazy. Go with the smoke.

I installed Carrara marble in my bathroom about a year ago and had originally planned on grey grout but let my tile guy talk me into off white as being more traditional...wish I had stayed with the original plan as it is hard to clean and already discoloring, it looks grey but not in a good way....so I am down on my hands and knees scrubbing the hex tile grout on the floor with a toothbrush!

I think there is some confusion about your question as I reread your post and from the first picture it looks like you are asking if you should use white or grey but then it seems you are asking about lighter or darker grey from the second picture...I would go with the lighter grey as this will not discolor but will also not be too high contrast (unless you like that look)

Silver ! You can have the grout sealed! You might have to do it but aesthetically you will do well.

what did you choose? do you have finished photos of the grout?