As long as the bathroom still has space for a decent shower, Id go for the laundry.

That depends entirely on how small the master bathroom would end up being (and the layout) if the laundry is on the first floor.

Laundry.

https://www.houzz.com/magazine/where-should-you-put-the-laundry-room-stsetivw-vs~35155424

Once the master bathroom is adequate for the user needs, then a laundry suggested.

If this master suite is meant to be for future retirement, a laundry would be very useful to the users on same level to avoid going up & down stairs with laundry. I prefer on same level. I would not buy a home if wash/dryer meant going up & down stairs to basement.

My answer would depend on the market for that particular house. If it is a primarily family neighborhood, I would favor the bathroom. But, in a smaller house, especially in an area with significant population of homeowners without school age children, go for first floor laundry

My concern for a family neighborhood is families tend to have lots of laundry and if the laundry area was not large enough, it could become a problem area. Laundry closets are OK for one or two people, but not ideal for families.

Depending on the layout...and since second floors almost always have the bedrooms ...a stacked washer dryer in a closet would be good there ,too....

We built a bathroom off the master bedroom with the express purpose of getting the washing machine out of the kitchen and the dryer out of the dining room and into a better suited location.

When the foundation, framing, plumbing, electrical was being situated we thought that perhaps we had given too many square feet to the room. It was enormous. We were worried. Once the huge jacuzzi, shower, double sink, toilet, cabinets and washer/dryer were installed, it all worked out perfect. The moral of this story is plan for enough square footage for all of your large features to peacefully co-exist. As my contractor told me during the worried phase, he said once everything is put into place, the room will shrink by amazing amounts. Any smaller, and our bathroom with w/d would have been cramped and quite uncomfortable.

Btw, I really enjoy having the w/d in the bathroom. I know some people think it's odd, and I did too at the time not having had that sort of set-up prior, but we didn't have another location with our goofy house. That's the room we get underdressed in and dirties go in the hamper right there with the washer and dryer within inches. Kid's bedrooms are nearby and easy to get those dirty piles into the laundry. For us, it was a good move and I could not have been happier with the arrangement. I haven't had to schlep dirty or clean laundry since I built that room...very nice indeed.

The first thing I did when we moved here was move the laundry room from next to the kitchen to the bedroom wing where all the laundry is generated.

I kinda like my laundry room near the kitchen ...as I usually do our laundry when I am in the kitchen...cooking...cleaning ....etc...it goes faster when you can hear when the wash cycle ends...and immediately put things into the dryer...

I voted for a larger bathroom, but I would also be happy with a stacked washer/dryer in that bathroom. I've been dealing with a laundry closet for so long, I'm quite happy without a laundry room, and now kind of think of them as wasted space that I'd rather enjoy in other rooms. A stacked W/D pair and a few small shelves behind bifold doors would suit me fine.

Also a factor is how many people and what their ages/laundry producing capacity are. Lots of kids that get dirty and family members with smelly sports like hockey vs a couple with a 17 year old daughter who will be going off to college next year (for instance).