It is nothing but metadata. Why do it in camera unless you are shooting jpegs? It's faster to set it on the computer, and you can see exactly what you get in very fine increments. Do it however you like. But you aren't doing it the most precise, or even efficient way when you set picture styles in camera for RAW images.
I believe I understand the question perfectly too. BTW, I agree with Keith on the point of fact and I agree with Ed on the point of ease of processing...
But those comments aside and to the question 'just asking whats your favorite user def. Settings, if you use any in camera': I have several, none is a favourite, and all are specific tools.
I always shoot RAW + JPEG (L) and use CS3 for Post Production. Except for Weddings and Portraits, (if I use digital for Portraits), I mostly use the JPEG (L) file with only some Sharpening (pretty much a preset now) and Cropping to 5x7 in post production - usually 5x7 matt prints and / or web use images. I spent a long time tailoring the in-camera JPEG parameters to suit various shooting conditions I regularly encounter. There is a long thread on it somewhere... Search through my previous if you wish: but the essence is, many controlled tests under typical, different lighting conditions = a 'set of parameters' The other point of note is, the parameters are “different” for my 5D and my 20D: what I mean is (as one example), for a particular Indoor Swimming Pool one increment change of 'contrast' on the 20D is equivalent two increments change of 'contrast' on the 5D. I understand perfectly.O.K. I stand (sort of) corrected.