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.
If it was me, I’d go with a cabinet install that allows for a 24" dishwasher. That’s the standard size, and you might have trouble replacing a broken 18" dishwasher in the future.
18” dishwashers are still very easy to get ahold of. I’ve recently replaced one and while I had more limited options compared to 24”, there were still dozens to choose from.
I’ve gotten some good deals on lightly used 24" dishwashers. I’ve never seen an 18" come up, though I’m sure they’re out there. I think I paid about 50% of MSRP on my current one that has been very good to me.
I see lots of people saying there are plenty of 18"s, and I’m sure that’s true if you buy them new. I guess I just wanted to agree with you and share my experience.