For water based, I love Zig Clean Color Brushes and they blend very easily too - you might have a little more head scratching to do to find light/med/dark reds/blues/greens that you would with Copics. But I could be wrong.
I have tons of older Prismacolor pencils I needed for classes years ago, and they blend very nicely. And they're budget friendly, plus can be purchased individually at some stores. I said "older" since some people have said when they moved their manufacturing, the quality changed.
For alcohol and a great selection of light/med/darks of your colors, I like Copic maybe the best, since you can buy individual greens, blues and reds. The Copic Ciaos are less expensive than Sketch. The ink is identical. The Ciaos hold a little less ink but can also be refilled. My instructor, who said she has used them for 20 years (?!), had both in her stash.
Lots of on-line shops sell them, including Dick Blick. You'd want to watch a video or two about blending. It's not hard, but seeing someone do the technique makes it easier. And the manufacturer has lots of resources, including charts that show you every color. Copic experts here (I'm not one!) can help you select which blues, reds, etc., too, if you'd like. Here's one of the color charts from the manufacturer:
https://imaginationinternationalinc....wheel_2014.pdf
You'll also want good cardstock that "likes" to be blended on. Enjoy!