I personally think some of the best cars, by any manufacturer, have already been built, keeping in mind what they were in their day, and some of my opinions are based on those with experiences senior to my own.
Some of my top picks from some of the bigger manufacturers:
Toyota:
1980 through 1983 Corolla (the rear-drivers)
1990 through 1997 Corolla (4A-FE)
1987 through 1991 Camry (3S-FE)
1990 through 1994 Celsior (sold here as the LS400)
1998 through 2005 Aristo (sold here as the GS300/400/430)
Nissan:
Any VG30-equipped car or truck, from about 1985-on (this excludes most any newer Nissan). Like a 1993 Maxima... excellent car.
The last of the rear drive 200SX was a very good car, as was the mid to late '80s Stanza, with the twin-plug belt driven 2.0L SOHC engine.
Mazda:
1986 through 1993 B-trucks (I personally drove one of those to over 400k miles before a deer tooefed it).
1985 through 1991 626.
1985 through 1994 323/Protege, with a special nod to the 1991-1994 Protege as those were a fantastic little car for the money.
First generation 929 (the boxy one, with the SOHC 3.0L).
First generation V6 MPV (same engine as the above 929).
...most anything after that started to go downhill, with Ford's influence ultimately spelling the demise of the "old" Mazda.
Honda:
Any Civic prior to 2001 is a great car. 2001+ are crap piles in comparison, sorry.
Accords through 2002, with the 1991ish models probably being the best all around car (this was the car that really put the Accord on the map).
The Legends were stellar cars in their day, an all-around top notch car, especially the earlier ones (1985 - 1988).
Mitsubishi surprisingly has pulled together more recently, I would say they have some of the better stuff they have ever had in recent years. I have to say, I just drove my 1995 Mitsu on a 3000+ mile trip and it performed well, though.
Ford:
They may have their best stuff yet in the [North American] showrooms right now. Too bad they insist on truncating the engine choices here.

But the Mazda 323-based 1991+ Escort/Tracer was a pretty decent all around car. The Kia-supplied Festiva was a pretty good little car, too, believe it or not.
GM:
Like Ford, I think they have some great stuff available right now, and I was really impressed with the new Aveo and Cruze at the auto show, as well as the new Buick Regal GS (and that even had 3 pedals!

). The best car to wear a GM badge in the last 25 years though is probably the Nova/Prizm (which is a rebadged Corolla

).
Chrysler:
...we'll have to wait for Fiat to see what pans out, but other than the Challenger's mullet-factor, I do not see much else there to write home about. Yes, I know the Cummins engine is available in the Ram, but I do not need to move an apartment building around with me any time soon... or ever.

But as far as "good cars" to come from ChryCo, laugh if you want but the old K-cars were actually pretty simple, stout, solid, and reliable. EFI helped, so 1985ish+ any FWD car would be my pick. Boring, ugly (save for maybe the Daytona), but they were not an unreliable car all things considered.
HMC:
I think any 2000+ Hyundai/Kia product is a pretty well sorted car, even if they are a couple steps behind on engine technology, they seem to work well enough. HMC has rid the Kia lineup of any of the old models/platforms.