My opinion only, and note, I have not yet taken both, but this goes from what I've seen in demo's and samples of each, as well as from folks I've spoken with, who HAVE taken both.
(And I agree with what Dark_Knight JUST responded...)
Cost-wise, obviously OSCP it better. (MUCH cheaper) Thus, if you're not 'absolutely' certain you want to be a pentester, or want to see just how much you might get into and learn, it'd be a more affordable way to begin. That way, if you feel over your head and decide against it, you're not out the SANS-type money. But if you truly want to have opportunity to learn and understand more, SANS might be the better route, especially if you're willing to go to one of the bootcamps, as the ability to interact directly with an instructor, for info you may or may not understand, is very valuable, in and of itself. BOTH will be technically challenging, and both will introduce you to concepts, methodologies, etc. As previously noted by Dark_Knight, the legalities, etc, are also nice to gain from the SANS offerings.
We really cannot tell you which is better for a 'beginner' as it depends on you. If you're a GREAT self-learner, then a 60-day lab package and OSCP might be good for you, as it gives you a LOT of lab time, and hands-on practice with tools and ideas, while still affording you the ability to email the instructors and irc with other students, etc. But if you learn better from more 'regular' interaction with instructors, in more of a class setting, then I'd definitely be leaning towards SANS to start with. (Additionally, if you do opt for a bootcamp, you also have many other folks at the SAME point in the class as you, to openly discuss with and network with during the course.)
Ultimately, to answer your question, I don't think either would 'win', and that each is tailored for it's own learning style and methods. Personally, if you can afford one or the other, in my opinion, I'd do both (the extra for OSCP isn't THAT much above the SANS, anyway...) Then you'll get it all.
My 2 cents, anyway...
~ hayabusa ~
"All men can see these tactics whereby I conquer, but what none can see is the strategy out of which victory is evolved." - Sun Tzu, 'The Art of War'
OSCE, OSCP , GPEN, C|EH