First off, you need to more clearly define what you mean by the word "Saab" There are three major types of true Saabs, all of which are part of an evolutionary series. They are 92/93/95/96/Sonnett (47-80), 99 (69-84), and 900 (79-93) The 9000 was a joint venture with Fiat, Alfa Romeo and Lancia, and later models are reworked Opels, with the exception of the 9-2, which is a thinly disguised Subaru Impreza, and the abomination that is called 9-7, which is a Chevy Tahoe.

The real Saabs are in many ways more technically advanced than the corresponding models of Volvo. Does this mean they are better? No, not really, just different. Build and material quality are pretty comparable on both, as are ruggedness, safety and durability, with the exception that most Saabs suffer from weak gearboxes. This is due to an engine with too much torque in the 96 V4 and a design flaw in the 99/900. In my experience, Volvos are a lot easier to work on, though I'm not very familiar with V6s, diesels and Turbos, all of which have added complications compared to the red block fours.

In stock form, the 900 (79-93) is more sporting to drive than a 240 or 740, but a few easy modifications will bring the Volvo up to par.

Probably the best way to describe it is that there is a major difference in engineering philosophy, rather than one being better than the other. RWD Volvos are a very conservative design, refined over the years, while Saabs (real ones anyway) are much more avant garde. Saab's other product line was jet aircraft, Volvo's was heavy equipment. Take your pick, they're both well designed and built, with the exception of a few stupid flaws (740/900 headliner, 240 heater fan, 99 water pump, etc.)

None of this applies to more recent models, neither of which appeal to me very much. If I had to choose, I would probably take the 850/V70 over the Opel 900 or the 9-3, as the Volvo was designed from the ground up, whereas the late Saabs are modifications of an inferior car (Opel)