best pen display tablet for illustrator

A couple of things are unclear:

Do you just want high fidelity stroke recording for the sake of it, without needing any handwriting recognition for your notes? When I hear about students taking notes, many want their handwritten notes to be recognized as text so that it can be searched, and copied and pasted as text into other applications. They use note-taking apps such as OneNote that can freely mix typed text, graphics, and handwriting recognized as text content. But if you record strokes using the pen or brush tools in Illustrator, they will be “dead” strokes that will look nice and can be styled, but cannot be converted into searchable text content.

Do you want a “pen display” or a “pen computer?” Those are two different things, but your list mixes them.

• If you want what some companies call a “pen display,” you can use it only if it is connected to a Mac or Windows computer. It’s just a peripheral device, simply a monitor that accepts pen input.
• If you want a “pen computer,” that is a standalone iOS or Windows tablet so you can pick it up and work anywhere without bringing anything else, because it has its own operating system and an internal battery. If you need portability and the ability to work without an computer attached to it, you want a pen computer, not any of the pen displays.

In your list:

• Wacom Cintiq Pro 24 — Pen display. Works only if connected to a Mac or Windows computer. If you want a Wacom pen computer, you want the Wacom Mobile Studio Pro.
• iPad Pro 12.9in (5th generation) with M1 chip and Apple Pencil 2 — Pen computer running iOS. Highly responsive, low parallax. Runs Illustrator for iOS, which is a good app, but lacks features in the Mac & Windows versions of Illustrator. I have taken handwritten notes in various apps with the iOS Scribble feature, which converts handwriting to text, and found that works quite well although not perfectly. But Illustrator on iPad does not seem to accept Apple Pencil handwritten input at this time; as in Illustrator for Mac & Windows the strokes you draw are graphics only.
• Huion Kamvas Studio 22 — Pen computer running Windows. Looks like it’s based on the Intel Core i5.
• Huion Pro 24 — Pen display. Works only if connected to a Mac or Windows computer.

For the pen displays, quality of drawing is not just about which hardware you buy. It will also be affected by the quality of the Wacom or Huion tablet driver software; interacting with the performance of the application (Illustrator), the operating system, and the graphics driver working together. That is a lot of variables. I have tried both recent Wacom and Huion pen tablets (not pen displays); my own anecdotal experience is that I was disappointed with the quality and performance of the Huion driver software. But others like the Huion line, so get more opinions.

I would get a Windows one, as good as I hear the Apple pen etc. is, as you'll be able to install the desktop version of Illustrator rather than the neutered iPad version.