I've owned an '83, two '84s, two late '85s, an '87 S, an '88 automatic and now an '89 S2. I've serviced dozens of 944s of all variants (Turbo, etc.).
My all-time favorite is the S2, any year. The most refined, the best combination of power and torque
curve, overall just an incredibly solid car. Probably the all-around best car I've owned. And when you factor in late 944 features such as ABS, premium sound and air bags, it's seriously in a different league over the early cars.
I agree with arominus about the S. The car is deceptively quick, and handily faster than the 8-valve NA cars. You will really get the best of it and exploit its power by being in the right RPM range and right gear for a given speed -- and it's not difficult to find this -- I agree with arominus again that it only takes a few minutes of driving it to "get it". You really notice this on the freeway with the car's ability to pass. It is smoother, too. With all that said, I ultimately sold mine because I was doing a lot of highway travel at the time, and could not stand the fact that it was turning more RPMs in 5th gear than my 85.5 NA was. I sold it to a friend and am happy that he is still enjoying it.
I really like the simplicity of the early cars, but if you're going to go that route, I say go all the way and get an '83. In addition to being lighter, the lack of power "almost everything" suits the 1970s style and ethos better. Calling the power steering "leaky" and problematic, however, just means you've only ever owned an old car with an old rack!
I don't think there is anything particularly desirable about the 1989 2.7 cars -- they are heavier throughout, and the extra power is only compensating for the weight gained over the years. And the '89 has additional weight over the previous years, such as a beefier exhaust system that makes draining the transaxle a little bit more of a chore than on the earlier cars. But for performance -- particularly acceleration -- I'd take a light weight '83 over an '89. The one thing I do like about the '89 model year is the additional paint and interior colors as well as interior options (you see more split seats, premium sound, etc.)
To me, the "nothing" years of the 944 are '84-early '85, and '87-88(NA). Awesome cars, but these are not the standout years -- average performance, no particularly enticing options, few variants on the interiors, most are the same handful of exterior colors, lacking the raw simplicity of the '83s and the advancements of the latest variants. But every 944 -- even a plain guards red or silver 1984 with black basic interior and cookie cutter wheels with an automatic and all the wrong options -- is an AWESOME car.
Cheers,
Tony K.