An ideological question: iPhone "n" or iPhone "nS"?

Where "n" is a number (as in 4 or 5, yes I'm aware the 3G doesn't fit this perfectly but stop being pedantic) and "nS" is the "S" version of that model (3GS, 4S, possibly 5S). Let's also assume you're sticking to the typical 2 year contract/upgrade cycle.

Which do you prefer to get the first iteration of the design (say iPhone 4), or the improved S version (4S)?

(I'm in the middle of this dilemma, kind of.)