As someone who lived through the 90s where a well written email could see your domain terminated, a reputable registrar meant way more than low prices. And in some cases even expensive ones would rule against you (looking at you netsol).
1) They had a good reputation on here at the time (10 years ago?)
2) They have a nice panel for DNS config
3) I wanted to separate my registration from my hosting
4) I think it's a pretty well-known registrar
I'm concerned by the OP, though.
Before that you were much better off using a registrar with a known dispute process (verisign) or in a jurisdiction which required a legal precedent (German registrar joker.com leapfrogged into stardom during this time)
Also the process of locking domains came out of these actions
Made self-hosting interesting when your home IP changed, or you moved, and that was where you hosted your DNS and email.