I am currently redesigning my kitchen in a 1930's Midwestern USA house. The kitchen has a decent floor area but the floor plan is oddly restrictive.
My space next to the sink is such that I can either have a standard 24" dishwasher next to the sink and a slightly weird cabinet adjacent to it, or I could have an 18 inch dishwasher at 45 degrees flanked by two small but reasonably sized cabinet doors (or drawers), although the 45 degree plan would dictate a somewhat shallow custom counter depth on the flanks (like 18-20 inches).
I think I would be more proud of the accomplishment of building the angled design, and I think the ergonomics would be optimal.
But I'm not sure about the smaller dishwasher. I have never used a smaller one. It seems like it would be enough for my small family and still plenty helpful for gatherings.
I got the feeling that the other commenter is right, that you’ll hate it, every day going forward:
Choose dishwasher over cabinet: every time you don't use the dishwasher's full capacity, you'll wonder why you didn't go with extra cabinet space instead
Chose extra cabinet space over dishwasher: every time your dirty dishes are too much for your dishwasher, you'll wonder why you didn't go with bigger dishwasher instead