The best sewing desks are the ones that fit you. At the end of the day, the machine doesn't care about where it's sitting, but your body sure will.
I'm short, so I needed a shorter desk. All of the desks I saw were pretty much the same height. My shoulders were around my ears, my back super stretched out, and I felt like I was reaching for everything. Yes, you can take some of it up with an adjustable chair, but feet dangling in the air is not good for your legs. Yes, you can use a step stool or something to elevate your legs too.
And -then- I saw the price tags. I can buy a lot of fabric and vintage machines for that! And I was going to have to modify or add things to make it fit me?
Or you can fit the desk to you.
The same goes if you're not height challenged.
Something that can recess at least your main machine is best. You'll fight the fabric less, and not be as sore as a result. Something that can recess any machine you have (if you have more than one) is the ideal.
As a general rule, something sturdy and made of real wood or metal will hold up longer than something that's made of man made materials or wobbly. Particle board should have the screws tightened once a year. Additionally, a heavier, sturdier desk will absorb more vibrations from the machine, especially the heavier and high speed ones
These were my requirements. The desk I wanted didn't exist. I'm one of the QBers who built / modified.
We cut 2" off the bottom of the legs. We cut a hole that would accomodate any machine I have, and cut Lexan inserts for each machine. We created a height adjustment for the machines to be level with the top of the desk. We routed the ledge for the insert to sit on. This was all done to a Government surplus desk.
When I say "we", I don't mean the royal "We", as in I gave DH the instructions and said bring it back when it's done. I did as much or more of the work than he did. With a little time and patience, you can do all of the work yourself. The only tool that consistently over challenges me is the router. I'm sure you could get DH or a family friend to route a quick ledge if push comes to shove.