I'm a part time student and work full time. My opinion is basically that if you can afford a bigger screen area than the 9th gen iPad to go for it. The larger screen real estate is nice when taking long notes.

As such, I think a refurbished/ used iPad Air 4 makes the most sense from a cost to features perspective. That being said, the iPad Air 5 is also great for notes but the improvements over the iPad Air 4 mainly come down to a more RAM, a better processor, and more advanced multitasking, something a note taker/ streamer wouldn't care about for years. The other big benefits of the Air 4 and 5 have over the iPad 9th and 10th gen is that they have an anti-reflective coating which can make a big visibility difference in a brightly lit classroom or office, assuming there isn't a matte screen protector applied. The other benefit of the Airs over the iPad 9th gen (not 10th) is that they have better speakers which is nice when watching YouTube without headphones.

For note takers who aren't interested in drawing or other workflows requiring pressure sensitivity and want to save money, get a third party iPad compatible stylus like this one for a fraction of the cost of the official Apple Pencil.