I have worked out for many years and in many different gyms. One thing they all seem to have in common is the hex weight dumbbells. When we decided to build our own home gym, one of the first things we purchased was a few different sets of these hex weights.
These Body Solid Hex Weights are great because the shape prevents them from rolling around on the floor or weight rack. The handles are etched with a diamond-shaped patten to help with grip. This does help when you start to get sweaty, but it also starts to hurt when dealing with the heavier weights. I always use gloves when I lift the 10 pounds and up.
They have gotten nicked and scratched, and the ones we have had for a few years have some rust in these spots. It's minimal and doesn't bother us when we use them.
These weights come in a wide variety of sizes ranging from 5 pounds to over 100 pounds. They are sold by the weight, not the piece. We always buy 2 of each weight so we can work out both arms at the same time, but to keep the price down you might want to just buy one of each.