Banknotes are cooler. Chicks dig'em In all seriousness, there are a lot of advantages to collecting notes over coins. Better face value to market value ratio. I can also fit 10x (more actually) the amount of notes in my safe deposit box than I can coins. There are more advantages but those are two big ones that come to mind. The only disadvantages I can think of are intrinsic value (paper vs metal) and notes are less popular than coins (at least for now) so there are less resources and readily available information.
There are many more varieties of notes.....Federal Reserve Districts....batch numbers....star notes....etc. There might only be 1 or 2 or 3 Saint-Gaudens coins in a given year. There could be 20 different collectible versions of a certain bill, though usually most are interchangeable.
I just got into bills in the last year....ironically, I went over my mother's/grandmother's old Silver Certificate collection (mostly worth FV) and that kind of jumped my interest in bills. I had always wanted a nice Gold Certificate and a $500 and $1,000 bill. Also wanted a $5,000....$10,000...and $100,000 bill.
Very nice to see another that likes pound notes like I do. They are an addiction I have had for a wee bit of a long time. Really appreciate the Provincial £20, Provincial was a very small Irish bank that issued notes very scarcely. So far I have only acquisitioned the £1 from 1940. Canna wait for Jonathan Calloway's Irish banknotes catalogue to come out early next year.