"What are the best paints for figures?" is a tough question to ask, because there are going to be almost as many answers as there are painters.
I use acrylics, primarily, because they go on and cure thin. You don't want to build up thick layers of paint. Andrea and Vallejo are popular brands among figure painters who use acrylics. I have some of both, as well as Tamiya acrylics. Tamiya acrylics work well, too, but they must be thinned, and I found I get the best results with Tamiya's proprietary acrylic thinner. I thin the others, too, but using water; I'm working more and more with a wet palette, an air-tight container that includes a sponge to hold water and keep the paints hydrated, and a membrane--brown packing paper, in my case--on which I put the paints and blend the colors. I use this to build up layers of a color, thinned so much as to be a glaze, till I have the colors and the shadows and highlights that I want.
Andrea and Vallejo have specific color sets, but I also received as a gift a set by Lifecolor, a WWII US Army colors in the ETO for 1944-45. They work as well, thinning with water.
I also use oils, but I have found acrylics easier to work with. Oils are applied, thinned with mineral spirits or turpentine. Oils have the advantage that they dry slowly, so you can take your time blending highlights and shadows. You can also speed the drying time using a 60w lamp; some guys use a crock pot, especially those little potpourri pots that were popular back in the 80s and 90s. The low warmth helps dry the paint without causing it to crack. I have Schminke-Mussini oils. But as I said, I've found acrylics easier to work with.
I have some enamels, too, mostly Model Master. I apply these by thinning with mineral spirits, on a ceramic palette.
For 1/48 figures, like the aircrew from the planes I build, I lay in the basic colors--khaki or tan, or OD, for example, and flesh for the faces. For eyes, I usually just paint a thin line and add the eyebrows. Then I paint the details--straps, packs, etc. Next I add some highlights and some shadows, using the base colors to mix the highlight or shadow colors. Then I just use washes to flow into the relief and tie everything together.
I agree with Gamera, that it's not necessary to buy a lot of paints. A set can help if you're not sure about which color to use, but I do what he says as far as flesh colors go. Both Andrea and Vallejo have colors for Caucasian skin, for example. They have the basic skin color, then they have a darker and a lighter version. I just bought myself those three colors, and if necessary, I'll use other colors already in my paint box to modify them as necessary. A burnt siena or a burnt umber, for example, can be used for a lot of shading or modifying base colors, or for a wash. And for colors like OD, I pretty much use a jar of OD, and then shade or highlight as necessary. I don't see the need to have several different shades of OD, from various makers, when I can get the result I like with the one jar I currently use.
Hope that helps!
Brad