[thstone]

The age old rule is to buy the newest and best condition Porsche that you can afford.

With that being said, all things cannot be equal - the age of a 986 S will always be greater than the age of a 987 base. The hard part is comparing years vs miles: which is better, an 03 S with 50K miles or an 06 base with 75K miles where both have similar prices? The answer is in condition. The better cared and maintained car will generally be the better choice.

Another rule is that you should drive both cars yourself and decide which you personally prefer (because all of the S owners will say "buy the original S" and all of the base owners will say "buy the newer base").