I think it just depends if you want to mod your car remap, cold air intake and so on then the s3 is the one. If you want to just listen to the v6 soundtrack and enjoy then the r32 is definitely the one for you.
I had to decide between an r32, s3 or golf mk5 GTI and considering I may have to drive to work in it every so often I just went for the GTI DSG.
But seriously considering the r32 if I can next year that sound is just priceless and if I was going to buy an s3 I'd want a facelift, which is out of my price range currently. I'm also 21 by the way.