I eventually ended up settling on Amazon too. In the past I had some domains with my hosting company, some with iwantmyname.com, and a couple with a local regi

I eventually ended up settling on Amazon too. In the past I had some domains with my hosting company, some with iwantmyname.com, and a couple with a local registrar (because buying Finnish domains (.fi) requires a personal ID, and most registrars didn't support them). I started getting annoyed that they were spread amongst different registrars, and I couldn't look in one place to see when things were due to expire. So I picked Amazon as my registrar and moved everything there. (The good news is now they support .FI domains too!)