I would like to write down my seed phrase but I am hesitating between writing it on a sheet with a pen or typing it on my notepad app on my computer and print it ?
Which one will last longer ?
As said, it depends on too many variables. I've seen erasable pen, which also fade in time. The receipts are printed and do fade (I think it's thermal and not the best example, but still).
But a proper pen (usually ball pen, I'd guess) or marker would do. A proper printer would also do, just keep in mind that adding printer into equation is usually considered lowering the security.
Also as said, if you laminate it'll be better.
I'll add that you should also store your seed (in a way or another) in multiple (geographically different) places.