I would not paint the fireplace rocks white! Looking at your floor and color of machines you can tie in the colors of the stone/facade beautifully and make it a warm, cozy-feeling space by painting the walls something that pulls it all together, and that something-color is not white.

I agree with leaving the stone "as is". It works, and who has stone in a laundry room?

If you're putting in upper cabinets, I'd also go with a dropped ceiling to cover those ducts.

I'd go with a set up shelves on one side of the machines, which could hold "waiting loads" and detergent.

For looks, the first thing I'd bring in is a colorful rug to lie in front of these machines ... something in your favorite color ... with a stripe or print. Then some pretty prints for the wall in similar colors.

I don't know your ceiling height, but it may have been possible to stack the wash/dry with a simple stack kit. Hide the venting, and free up storage, and get more counter space.

Dimensions/a drawing of the space as is, would lbe helpful,. we cant see the other wall.