I wish I had experience with them, but I have never fired either. However, I did just purchase a Ruger SR40, and I like it quite a bit. It is also in the same prize range as the Taurus. But between the S&W and the Taurus? I would go with the Taurus. In fact if my LGS had a Taurus available, I might have bought that instead of the SR40....
See, we all need more money because we shouldn't have to make these choices -- we should just buy both!
I own a sw99 in 40 cal and have shot an oss in 9mm. They are both great guns. But personally i prefer the sw due to the fact that i love the grip on this pistol, and some people dont like it, but i really like the AS trigger on the sw99. It feels alittle mushy in SA action, but once you figure out the pull it great. I shot alot more accuratly with the sw99 even though it was a 40. That being said. Im actually looking to get a 9mm for cheap as a back up gun and im looking into either the OSS or the PT99. But im not sure if there are 2 versions of the pt, ive seen one that looks similar to a 1911, not the one i like.
Honestly if you can try rent or shoot these at a range.
I own the 24/7 OSS ds tactical model in 40sw and it is a dream to shoot. We used to take a 3 pound coffe can (roughly the size of a human head) and would put it out at 100 yards just to mess around. We could consistantly put rounds into it. When we were really trying I put 13 out of 15 into it. I used it as a cc gun and I'll admit it was a bit bulky but it got the job done. I have several Taurus firearms and I wouldn't trade them even for some "higher grade" firearms. I have fired the Sw 99 and it is a good gun but I perfer the 24/7.