Gotta agree with Gambba in that it does depend on the style and capabilities.
I haven't been fortunate to get a M3 but have toyed around in a 328ci, for me it was a very nice car and was smooth, but the RWD (though the ultimate driving form) was not for me. My main gripe was not being able to get a smooth driving line out the the beamer when I was hurrying down a nice country road, I guess my inexperience of RWD at the time didn't help and really I never acquired that driving technique. I think with getting a EvoM3 you must have that acquird taste, otherwise you may wrap it round a tree off that bend you thought you could get round that little bit faster.
Anyways, since then I have stuck with 4WD cars: a 210hp S3, a 276hp EVO6 and a 225hp S3) as I prefer the traction gained and the knowledge of all 4 wheels helping me get the power down, rather than being a drag racer relying on your rear wheels.
Naturally the EV06 was something else it really was f**king awesome and that really was a different drive to the BMW and the S3, as it was a mixture of both. If I have 25K to spare I would get a EVO6 defo 19K for a good example and the rest spare rfor insurance, tyres and the 4500 miles servicing required don't forget the 45ltr tank that does 90-130 on a cane /ubbthreads/images/graemlins/burningmad.gif.
However I always went back to the /ubbthreads/images/graemlins/heart.gif S3 , mainly as this car had everything that you could imagine in terms of toys and more importantly was 4WD. With the S3 you have climate control, leccy everything, leather seats, 6spd, xenon, 4wd, but then you have the engine a 1.8T on AVS (therefore servicing every 15/20K miles compared to BMW every 10k (I guess?) ). You also have the exclusivity of owning an S3, M3's yes may be more pricey and have that pedigree of being a B M W, but they are common IMO. Yes you have 321bhp turning out under 6 secs, with the 210 you have 6.5, get a chip to get to 265 and then you'll have your sub 6 sec (I stand corrected, as I haven't got into tuning...just yet /ubbthreads/images/graemlins/idea.gif).
They are two very different cars and should be weighed up from all angles, not just looks and power, but utimatley the driving style that is required as well as how comfortable you are in the cars, as you'll be paying a few thousand on the car and the insurance, so you better make the right choice.