Help me with my 'new' car shortlist

[mikehiow]

So after a year of constantly changing my mind, looking for cars that'll do everything I want, raising and lowering my budget, I'm finally ready to make the move on changing cars.

Last year I bought a w203 C-Class to replace the daily duties of my 182, leaving it for track days, autotests and the odd hoon. The thing is, whilst the Mercedes is lovely and comfortable, it bores me and I've managed to get the Clio out for about 5 autotest events and 2 track days during that time.

The nail in the coffin for the C-Class was a recent trip to North Wales where I found some incredible roads which were ruined by the car I was driving.

I now want something that I can drive every day in relative comfort, that'll be fun when I fancy a hoon or find a great road and can still arrive and drive at a track day.
Four seats are necessary and the rears must accommodate a child seat.

My current shortlist consists of;

E46 M3
B6 S4
R26 Megane

Now I know the Megane isn't quite in the same category or league as the previous two, but it can be close with a light tickle and what it loses in performance, it makes up in running costs.

E46 M3 scares me with stories of rear chassis cracking and astronomical parts prices, even if I do 99% of the work on my cars myself.

B6 S4 seems a little soft around the edges and horror stories of engine out to fix common chain guide issues are a put off.

So I'm left favouring a Renault Megane over an M3 and S4. This seems wrong? Is it? I guess I just need an objective opinion on the matter.

Help!