1989-1995 for sounds, and 1989-1997 for looks. Reason being because 95-97 had a nice wide look to them (possibly wider than previous years??) although definitely not as beautiful as earlier cars like you mentioned.But for me, nothing beats the F1 cars of 1989-1994... They look so simple compared to now, of course, but those cars were a handful to drive!
Imagine the 1991 Jordan with Ferrari livery