Can you clarify what you mean by "best"? Best as in longest-lasting on the road, best mileage, best innovation, best looking products, best management, best... ?
Are you also then specifying only companies that are still producing, or any from history? Of course, if they had been 'best', they'd still be around, hmmmm...
Sorry, but a pet peeve when something is called the 'best' - engineer in me cries out for the what, when, where, who, why, how,,,
Historically, there are many companies that were very innovative, best at creating new technologies for their day, but for whatever reasons, these firms nameplates are now gone: Cord, Auburn, Pierce-Arrow, Dussenberg, etc.
As to modern autos, I hate to say, but US firms, altho' improving drastically in the recent years, still have much to do to change their own culture. I've a '92 Toyota Celica GT-S, over 204k miles, gets ~30mpg, driving 70-80 mph, very little maintenance - and will drive this car until can't go any further. Then there is the '05 Honda Odyssey
, which really kicks tail, for a minivan.
As deuce mentioned also above, the US industry is, unfortunately, hurting, and unless there is a MAJOR shift in their culture/ways, in their dealings w/ suppliers, in their labour environment, etc., they will continue to falter. Unfortunate, in that there is much talent there, and also in that there is so many other firms relying upon their business. The domino effect here in the States is going to get worse, I am afraid, before it improves, if ever.
FWIW, if ever in the NE Indiana area, might check out: http://www.acdmuseum.org/
Wiki has a very quite long list of car manufactures: http://en.wikipedia.org/wiki/List_of_automobile_manufacturers