I like Rustoleum paints a lot. Six foot high cabinets are going to take several cans, but it's a very doable project.

Can also look into having them powder coated or sprayed at an auto body shop. I've only had patio furniture powder coated, I've never done anything thru a body shop just know people who have.

I have sprayed two-drawer metal cabs before. Relatively easy project.

Brown could look cool but black is classic and will always go with everything. I'm thinkin' black would just be easier since they're black to start with.