Collectability odds will be WAY higher on the 993 series (1995 - 1998) as Jupiter states. Porsche made and sold more of the 996 than any other series. (Ever wonder why there are so many for sale?)
If you want a 996 go for it, but don't plan on it being a collectable in this lifetime.
I owned a 993, so I'm partial to them. One of the big things for me is the interior - the 993 dash is still basically the same as all the 911's before it. Unfortunately, they tend to sell for more money already.
As for the steering wheels, many of the different variations of the 911 have different steering wheels within the series. The 993 for example, had both 4 spoke and 3 spoke (more desirable, common upgrade) wheels.