The larger the screen, the larger the typing area which means easier typing for notes, etc. But most university work is going to require a computer of some form, rather than a tablet, so you can download the software that is compatible with the school's requirements. You will also need a means to print at school, so a computer gives you more flexibility.
For now, the iPad Air is a good choice, but when you head for the university you will have to think in different terms.
I'll most likely use it to record lectures and take notes in class because the laptop I have right now is big and heavy and I do not want to take it every where with me because it is a big hasle. I wanted to get a little notebook laptop but my parents turned down that idea and insist on getting me the ipad hence why I'm stuck between the two at the moment.
Save some money and buy a min-tape recorder. Much better for note taking. But then you can also take notes the same way on an iDevice. An iPad Air is a good choice. You can get a nice add-on case and keyboard combo that turns it into a mini-computer much like the MS Surface. See 2014 MacBook Air vs. Microsoft Surface Pro 3.
As I said, the Air would be a better choice from my perspective since the screen/keyboard is larger. But you can also look into the Bluetooth keyboard options that you could add on to make typing even easier.
At some point in your university life you will want to look into a laptop, but that can wait for now.
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You might consider getting a refurbished iPad for less than the regular retail price.
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Has new screen, back and battery, and 1-year warranty.
Refurbished iPads from Apple