I have a TAF for a few years now, and I got SS during... 2 months tops, and I don't miss it. Both are easy, but TAF is just pure fun, and there are lots of differents things to do on it. Sometimes I don't play it for a while, but I *always* enjoy it.
On the other hand on SS, except if you're reaching for Spider Multiball, beating the game is done even if while not paying attention, and there's nothing else really...
I'm an average player, so if you're super-extra skilled you may find it boring, but even one local A player like it very much, as well as KME according to Pinballreviews.com.
TLDR; SS is fun, TAF funnier and better overall (except the sound maybe).