If you don't approve of pre-made,have one custom made.

Or buy a topless one and install a remnant for the countertop.

The ones you can buy online or from a big box retailer are meant to be freestanding. As you noted, it's hard to make them work as built-ins. You may be able to find a builder/seller of kitchen kitchen cabinets who will sell you a base cabinet with filler strips. Even big box stores can provide that. I prefer to work with someone else, but since almost everyone is near one of them, they will do if no other sources are available. Then as BPMBA said, go to a slab yard and get a quartz, quartzite or granite remnant for the top. This might be more trouble than you were hoping to do for a rental, but it's the only way to get away from the prefab look of off the shelf.

As mentioned, you can visit a big box store's kitchen cabinet dept and order modular base cabinets in what ever size required to compose the vanity of your choice along with fillers & a custom top.

These images and link are for the Diamond Cabinet line offered by Lowes.

file:///C:/Users/User/Desktop/DiamondEdge_2020_Web.pdf

Yes, Thank you. I went to Home Depot, they will only take on a complete bathroom remodel. Something I am not willing to do with a tenant in place. I spoke with a company that makes Ariel brand vanties. Lowe's carries them, they have color matched scribe, I can order filler and matching paint, that may be the way to go for the vanity. Now the countertop.... Even though it is a rental I want keep it looking good, it is in a complex by the water and values are high. I want to keep up that up if I ever sell.

It is interesting, I used to see remnants. They are more difficult to find. Several places that used to carry them no longer do. One place told me they have remnants but they do not fabricate the remnants.

You can buy a vanity without the top and have one made. As others have suggested, remnant slabs at slab yards and/or countertop fabricators are available at a considerably lower cost. I don't know if they still do, but Caesarstone used to have a half slab program for a few of their most popular colors. Ask a dealer about that, too.

Ceaserstone good to know it is a 36" vanity, seems a waste to buy a slab

What do you think about a waterfall application to the exposed side?

The countertop butting into the wall with a side splash but than having the gap btween the baseboard and the cabinet would drive me batty.

Right now the sink is offset because of drawers, I can see the sense in it not having your elbow crowded against the wall but isn't a center sink more in style?

If you have tenants, I'd advise you to consider CORIAN for the top. That material can be fixed if damaged.

you look for one that fits flush against the wall, and cut that side of the countertop flush. if you have a tiny gap, the molding should hide most of it. You could finagle a filler piece and paint it to match the vanity color.

I mean, it's a rental, not a million dollar home. if you want to look like the latter, then have a vanity custom made.

remnants or pre fab countertops are avail.

we put a 42" vanity in our rental from a Builders Surplus. it's a really nice vanity that came w/the top and the sink. and a mirror too. looks fine price was 800?1K? maybe? can't remember. We have very good tenants and they take care of things, so I don't mind doing extra for them.

you can also check craigslist and FB marketplace. I've seen some really nice vanites for a good price on those sites. remnants too

Beveryly, IMHO CORIAN is garbage. I had a home with a huge kitchen of CORIAN including the sink. The sink was so difficult to keep clean and it scartches easily. Plus last time I checked it was more expensive than granite. Beth, good idea about checking craigslist and fb. I may just do that find one that fits flush. I will prob have a custom quartz. I have had 30 lucky years of being a small time landlord with excellent tenants. I hope to continue.