Wow.. This can of worms hasn't been opened already?
That's actually a pretty hard question.
Both have had their share of Technological innovations,
Ford: Assembly line(model T), Mass produced V8(Flathead),Ford started the Pony car craze, Ford killed Boxy 80s styling with the taurus, They made the 1st hybrid SUV,
GM: First mass produced automatic transmission, First mass produced OHV V8, First production Turbocharger, They started the Musce car war,
I'd have to say GM, but not by a huge margin. GM has a tried and true engine fasmily that has its loyal followers. I see lots of Cobalts and G6es where I'm from, and that has to be some indication that GM's cars are selling better. My area is also crawling with Buick Lucernes and LaCrosses, so I don't think that they are as poorly off in sales as it's made out to be. GM has several cars that I think are good looking, and seem like a good value. (G6, Cobalt, Lucerne, LaCrosse, Saab 9-3 and 9-5, new Impala, new Malibu) Ford also has their European edge. Since the Focus, ford has been moving towards european suspension and styling. While they have a winner in the Fusion, Milan, mazda 3 and 5, Zephyr, and the F series and escape that are selling well, The Navigator, 500, Zephyr, Excursion, and Freestyle seem to be selling slow.
Sure, GM might have played a bad gamble on the GMT900, but I think that their new cars will make up for it. Plus, GM is the hottest seller in China, and if GM stays on top, (and the Chinese don't sell unlicensed GM copies) they could use the Chinese market to their advantage.
GM, because the Stovebolt is still alive. Somehow.
EDIT: Blazin, you do realize that Toyota's going to pull a GM on us and have massive recalls and lose customer faith, right? 50,000 lexuses (lexii?

) were just recalled because the seatbelts didn't work. Since Toyota has been in the passing lane, their recalls have increased exponentially.