Great question.
My ranking of jets that I have flown, favorite to least favorite.

747- King of the skies.
777- Queen of the skies.
L1011- Great room and feel.
767- ORD12 said it perfectly.
757- I have flown UA and DL one's a few times and I agree that they are a little cramped. But try it with Roll Royce engines (AA, CO, and AW). It's the best thrill ride in the skies since it's so over-powered.
A320 Family- Very roomy for a narrow body.
727- It's a classic. Reminds me of my youth.
A300/310- Always felt it seemed a little on the squeamish side.
DC-10- Great potetial and good comfort, flawed engineering.
717- Improvement over the DC-9 family.
737NG- Vast improvement over the classic 737.
DC-9 Family (including MD80/MD90)- Slow but I enjoy the 2/3 seating.
737 classic- Way too slow.
F100/F28-Feels like a toy jet.
EMB145/35-Like the 1/2 seating and corporate jet feel.
CRJ-Way too uncomfortable for a jet.

MD11, A330/40, Concorde, and Avro/BAE 146- Have not had the oportunity yet too travel on.