I only own 1989-1993 SCs. I prefer the look and it is what I am familiar with.
However, the 1994/1995 have airbags, 1989-1993 do not have airbags (but they have really cool motorized seatbelts instead).
1989-1992 SCs use the flaky Teves MKII ABS systems, 1993+ uses something newer and probably more reliable.
1989-1993 SCs need expensive and hard to find Crank Position sensors should yours fail. A 1994-1995 SC (from what I’ve heard) use a $25 Crank Position Sensor you can pick up from Autozone.
1992+ SCs have LEDs in the trunklid reflectors and have 18 gallon fuel tanks (more room for putting in a dual exhaust)
1989-1991 have 19 gallon fuel tank and reflectors but no LED.
Plastic windshield cowl for 1989-1992 are expensive and hard to find, cheaper and easier to find on 1993+.
I think 1994/1995 SCs got a factory pusher fan instead of a 2-speed puller fan. I personally put an aftermarket pusher fan in all 3 of my running SCs because I have overheated before when the puller fan wore out.
If I weren’t so attached to mine, I’d probably prefer a 1994/1995 SC.
Best thing going for the early SCs are the looks. I prefer the black side trim, the more square front bumper cover. 1989-1991 got stainless trim in the door panels, later ones dont. Early ones could have silly options like auto dimming headlights, maplights in the rearview mirror (1989-1990 with moonroof) and 1989-1991 SC have a vent in the moonroof (if equipped with moonroof) which is nice if you want the air to flow through without the sun in your face.
TLDR: get the 1994/1995.