There are a variety of watercolor palettes available what works best for you may be different from what works best for someone else. Here are a few of my favorites.
Zoltan Szabo Watercolor Palette. The palettes on the top of pile shown here has angled wells for the paint and angled wells for the mixing of colors. The angled wells for the mixing of colors helps the paint to pool at the bottom and perhaps stay moist longer. I love the rounded edges of all the wells, it's easy on the brushes. The separate walls in the mixing area will also keep the different mixtures from mingling. It comes with a lid and is great for traveling and plein air painting.
Tom Lynch Watercolor Palette. Has angled wells for the paint with high sides to keep each of the colors separated and it has a very large flat mixing area. This one also comes with a lid. It makes a great class palette. I love the rounded edges of this palette too.
Butcher's Tray Palette. This palette is a simple large rectangular pan with a flat bottom and four walls on the sides. It is an white enamel coated metal pan. I love it for storing colors I have removed from other palettes. I am starting to think it may make a great in studio palette, it has no lid. However, if I were to squirt fresh from the tube color and allow it to dry before using, I would have to make sure I choose colors that are not runny when wet.
Why have just one palette in one style? I think I have a total of 8 palettes.
I have excellent ideas for what I think the perfect palette should be and would love to someday have my own line of palettes and watercolor painting supplies!