The F1 was Canon's top-of-the-line pro SLR. The first generation model was a mechanical shutter, manual-metering camera (shutter priority automation could be had with an expensive add-on device), the 2nd generation, or New F1, had an electro-mechanical shutter (electronically timed speeds above a certain speed and mechanical slow speeds) and had built-in aperture priority automation (you only needed the AE finder to see the automatically set shutter speeds, AE still worked with the standard finder) and adding the winder or motordrive also gave you shutter priority automation. Both generation cameras were built like tanks to last for years in the hands of hard working pros.

The A1 was the top-of-the-line A-series "pro-sumer" cameras. It featured an electronically controlled shutter with both aperture and shutter preferred automation, as well as fully automatic program mode (and of course full manual). It also featured a digital LED readout of all exposure information in the viewfinder. It was not a "pro camera" in the sense that it was not built with the same ruggedness of the F1, although many pros used them, at least as a backup camera. A motordrive was available as well as a 2 fps autowinder.

Which is best? That depends a lot upon your needs. The F1 is better built (not that there's anything wrong with the construction of the A1, it's just not the tank the F1 is), but the A1 is smaller and lighter. Either one in excellent shape would be worth having for the serious 35mm photographer. As I mentioned in another thread about the A series: When shopping for a Canon A, keep your ears open for "the bird"; a high-pitched "chirp" that the shutter makes when in need of lubrication. An easy fix with a routine CLA, but figure in the cost of service when negotiating the sale.

Absolutely no argument against the F1 or A1 as quality machines. Just let me put in a word for Nikon's FM or FM2. They're solid, available at a reasonable price, plenty of lenses around, AND, except for the meter, they are completely mechanical so if the battery (or the circuitry) goes, you can keep shooting. This is not an insignificant advantage today as repair parts and repair shops become more and more scarce.

I used a Canon F-1n for years when they first came out and shot most of the Olympics with one. It is a system camera with a lot of equipment and it can do just about anything you want a camera to do and more. They are built real well and as close to a Nikon F2 as possible. The only thing that changed me to Nikon was the lens mount system back then but they changed to a similar mount as Nikon. Another drawback was that as a Pro ,,shooting with Canon equipment along with 50-60 other Photographers at times was a problem as they used mostly Nikon then. As time went by we all stuck with Nikon because we shared lenses amongst ourselves etc.,so shooting with a Canon didn't work out too well . As far as lenses and all the equipment Canon made for the F1 is concerned it is as good as Nikon made ,,just different,,and I wouldn't hesitate to buy one today if it has been takin care of. Just make sure it is the newer of the 2 models . The older version had a short throw film advance lever and didn't advance the film a full frame in one motion and it was clumbsy. The later had a bigger lever and cranked the film the full frame in one motion and had a bigger tip on the end. The last one was smaller and cheaper ( to me anyway ) and I wouldn't buy it.
The A-I was a cheaper camera aimed at the Advanced amature and not really a pro type of camera ,,even though it was used by some Pro's. I wouldn't buy an A-I today . ,,,,,,,,,,,,,,,Roy

I have been a Canon FD user for 34 years in freelance work, and have two of each (F-1 and A-1.) If you are starting out, I personally would opt for the F-1. It is a rugged, basic, nononsense, mechanical camera. The battery serves the light meter only.

The A-1 is more sophisticated with a steeper learning curve, and is an "electronic" camera - the battery contols the entire function of the camera, including the shutter.

If the battery goes on the F-1, all you lose is the light meter. You can continue to photograph with it, exposing with experience, chart aids, or a hand-held meter.

If the battery goes on the A-1, the shutter does not function. Done