This list reflects my personal preferences only and only stuff I currently own is on the list. All Grados are amped with a Grado RA-1. For everything else I use a Cosmic Reference (except the Lambda Pro which is a system and the Etys which I use unamped):
Grado RS-1
Senn GD-600 & HD-650
Stax Lambda Pro, Sony MDR-CD3000 (I tried these with the Grado amp once and I thought my ears were going to start bleeding!) & Ety ER-4P
Grado SR-325
Grado SR-60 & Senn HD-414
Koss PortaPro & KSC-35