Best high gloss black nail polish? I'd like one that is tough & long lasting.?

Try OPI or Essie. Also, Zoya is good!

Use a good base coat and ag ood top coat. Any black nail polish will do the job as long as you have a good base and good top coat.

I use ORLY bonder polish. It doesn't truly dry down, its always a bit tacky, so it holds onto the polish really well. I use ORLY for their black polish too, its just what I found on sale at ULTA. I use OPI top coat, and seal my tips. This is the greatest combo of base and top coats that I have found. THe bonder keeps the polish on the nails, and the top coat is nice and shiny and stays on. I have brittle nails, so they always end up with a few chips after a few days, but with this I don't get many, if any at all.

I'm a huge fan of Zoya polish for complete coverage in two coats and for durability. I'm also an even bigger fan for Seche Vite topcoat, which is very shiny. It adds 2 or 3 days to a manicure.

Zoya has multiple black polishes, although I don't own any. (I do have deep purples and greens from them and love them.) Go here and scroll to the bottom of the color selections. https://www.zoya.com/content/category/Zoya_Nail_Po... It looks to me like Willa or Raven would suit you, but they have multiple blacks with shimmer, metallics, and different levels of shine you can pick from.

BTW, they sell these at various beauty stores and online, but the Zoya website has the best selection of all the colors, and very detailed descriptions about each one.