I would do a freestanding 24” vanity.

Random but scraping the popcorn ceiling is an easy but messy diy, will make the space look much crisper & cleaner (dep on the age of your house you may need to test for abestos, but its simple enough to do that just google how-tos)

Buy a 24" floating vanity, and DO not tile the back wall : )

All it will do is call attention to the clipped ceiling.

I would do the 28" with the small fillers and a custom counter to fit wallto wall.No fancy shaped mirror just one wall to wall and a simple bath bar for lighting

do custom floating vanity wall to wall. we have an angled wall above vanity in a bathroom. we had mirror custom cut to fit full wall with bar light on ceiling at top

Buy a vanity that fits in the space and use filler strips but have a custom sized top made the fits the exact space. Another option is to do something completely custom for the space. See below.

OR,......select a smaller vanity that allows enough room to get a paint roller between the vanity and the wall. Don't kid yourself, you'll need to paint eventually.

A 28-inch cabinet can work with a wider, wall-to-wall custom top, but I would have the cabinet supplier and countertop fabricator confirm the combination before ordering. Ask them to check the sink bowl and faucet clearances against the cabinet rails, drawers and plumbing, and specify any support the top needs. Filler strips finish the side gaps; they do not by themselves establish how the top is supported.

For the fitted option, template the opening after the wall finishes are settled, since the width can differ at the front and back. For the freestanding option, compare the actual countertop width, not just the advertised cabinet width: a true 24-inch-wide top centered in a 29.5-inch opening leaves 2.75 inches per side before any new finishes. Mock up those gaps and see whether you can comfortably reach in to clean. That practical check may make the choice much easier.

Happy to share some advice if you need! Feel free to contact us 😊