This is a great thread, really interesting
I hope you dont mind a humble PAX offering some nonsense
Faves;
747-400 - The enormity is so impressive, and the entertainment system on the BA I flew on was also impressive. First and only ever visit to the flight deck, somewhere over the Atlantic enroute KMCO was incredible. Made even better by the welcoming Capt and FO
757-200 - Even as a PAX you can tell the performance is awesome. Flew on a brand new Britannia in the *nice* colour scheme to Cyprus years back, and then on a connecting flight with TWA from St Louis to Orlando. Must've been a fairly light fuel load as its a fairly short hop, and it was certainly light on PAX. Took off out of St Louis like an F-18 ! Also a big fan of the 767 both 200 and 300 as flown a lot on both, both charter and schedued. Just a nice familiarity about climbing on board and hearing the engines spool up
A340 - Flew this with Virgin down to Joburg. What I liked about it was the entertainment system, the huuuuuuge centre toilets, the pristine condition of the interior, the quiet engines. Downsides were that I felt it was underpowered, and this was exaggerated at Joburg due to its altitude. Thought we were going to rotate somewhere in the car park !
DC-9 - TWA, KMCO to St Louis. This has got to be the noisest thing I've ever been on. Some high pitched whine started just after engine start, and never ceased until we landed. Went somewhat to be replaced by the wind noise at cruise, but generally just felt like an old heap of junk !