Another vote for Kakoune. I think most people will find its approach a bit obtuse at first, but once it starts to click it’s pretty interesting.
Maybe if you’re a seasoned terminal veteran it will make more sense to you right outta the gate. I started using Kakoune not long after I started using the terminal much more heavily, so it was a bit difficult at first, but it has been and continues to be rewarding.
For example, select some text and press the pipe character, and then you can enter a script or shell command (sort, uniq, fmt, etc.). The selected text will be fed to stdin of the command, and then will be replaced with the output.
Combine this power with multiselections, which can be operated on in separate contexts, and you’ve got a stew going.