I have one of the f/3.5 models and two of the later f/3.5-4.5 models. Conventional wisdom is that the f/3.5 model is better. Here's why I prefer the f/3.5-4.5 model: The f/3.5 lens is larger and heavier. It has a close focusing setting which is too close for a portrait and without the setting, the closest focusing distance at the 105mm setting is not close enough for a portrait. I would rather carry and use the f/3.5-4.5 lens and if I need to get closer, I'll also carry a 50/3.5 Macro. The f/3.5-4.5 lens ls very sharp and easier to carry around. Both lenses can have problems with flare but shielding with one hand will usually solve that problem. What about the combination with the A-1? When I know I will be using slower lenses I prefer to have a grid type focusing screen. This way the focusing aids in the center do not black out and I can focus on any part of the without having to recompose. In most cases I will be using a Canon F-1 or F-1n with an LD focusing screen. The A-1 has what are considered factory interchangeable focusing screens (not easily changed by the user) and these screens are not easy to find. My A-1 has the standard focusing screen which I don't really care for. It's fine with a 50/1.4 but not as nice with slower lenses. I was not interested in getting an AE-1, mostly for the same reason, but I do have an AE-1 Program. That model has user interchangeable focusing screens. I have the standard screen, a plain matte screen and a grid type screen for the AE-1 Program. It mostly has the plain matte screen installed. Changing screens is not that difficult but not as easy as with an F-1.