Copic Markers are popular for their ability to blend. I used Chartpak AD markers before I used Copics, and I quickly switched over because they are low odor, non-toxic, and refillable. The Copic sketch edition are the most popular and come in 358 colors. These are oval shaped (so they don’t roll around), and dual tipped (one brush tip and one chisel tip). The brush tip is great. I find the chisel tip sort of useless and difficult. The markers work on almost any paper, but they can bleed onto the other side.
Copic Markers come in three other forms — original Copics, Copic Ciao, and Copic wide. The wide marker is just one giant chisel tip. The “original” ones have a square barrel and two tips — one is chisel, but the other is a different, smaller brush tip. They hold the most ink. Copic Ciao has the same tips as Copic sketch, but the barrel is round and smaller so they are slightly cheaper.
The biggest drawback for me with these markers is the price. They are worth it if you use them a lot, but start out by only getting the colors you really need. I have a pretty small collection, so I use Chartpak markers alongside the Copics.
Before you buy any, make sure you know how to tell which colors blend (all the markers have a code that tells you the hue, saturation, and shade). Learn how to use the markers before you try them! I was so glad I did this. There are tons of tutorials and introductory videos to get you started. Copics quickly became my favorite way to color, so give them a try! They work on pretty much every kind of paper, and if you use them right, your art is guaranteed to look good.