I didn't own nor drive any of the 2 cars...but I wouldn't think at all. BMW
my choice for sure.

Have you looked at the 05 Infinity G35 coupe?  I've been looking real hard
for the past several months and I've just about decided this is the new
standard.  Driving performance right there with the BMW, more power and
torque, more room, cheaper, resale as good as the BMW, better looks (IMO),
etc., etc.

I think BMW really screwed up the back of the new 3.  Looks like they ran
out of parts and stuck a Hyundai rear end on a BMW.  Or better yet, it looks
almost identical to the old civic back rear ends.  Interior styling is good,
but not great and getting a bit dated.  And, when in the world is BMW going
to recognize all of their cars should have leather seats as standard
equipment?

Just some food for thought!

FWIW heres my thoughts, I have an M3 and I test drove an S4 some time back.

Seen a few old style 03/4 RS6's etc around quite cheap and Audi website has
a new RS4 and S4 on it.

BMW, M3 residuals will take a knock when date for new one confirmed although
this is (according to most) at least 12-18 month away. General feeling on M3
boards is they have already taken a slight knock with the E90 being
launched.

As you have discovered Audi is not as involving to drive but it is a more
relaxed and possibly refined drive. M3 can be a bit harsh but depends what
you want.

Looks... IMO Audi doesn't look as sporty or dynamic. It looks like a cruiser
where as M3 is a bit more agressive. But BMW looks are diluted by the number
of 318 Sports with 18" alloys. M3 doesn't look any different to to
uneducated.

Exclusivity... I live in the back of beyond yet I saw 3 other M3 cabs
yesterday, didn't see and Audi S4.

Performance... BMW is quicker but not*that* much on the road plus V8 is a
bit lazier in its drive to the BMWs racier 6. Top Gear did a good comparison
and the S4 came out a bit quicker round the track but the M3 was quicker in
a straight line. They chose the M3 overall because they liked it hooligan
approch with DSC off. Audis aren't very good hooligans.

I think that the S4 sits somewhere between the 330 and the M3, the RS4 is
between an M3 and a CSL. Its difficult to make an even comparison. I'd say
an M3 is aimed at a 30 something work-hard, play-hard. The S4 is for the 30
something whos workd-hard and played-hard and needs a rest.

I can't see BMW doing an M3/M4 tourer as its not part of the M heritage so
my next car is likely to be an RS4 or RS6 Avant due to growing kids etc plus
I'm reaching the "need a rest" stage ;-)

You've almost answered your own question. If it's the driving dynamics that
mean most to you, you've already said the BMW was more fun. If the looks are
more important, then you sound like you're leaning toward the Audi.

So which is it? :-)