I'm seriously considering a Cooper S to replace my aged but super reliable and efficient DERV A4
The missus had an 08 (turbo Peugeot motor) which was a riot to drive.. When it worked.. Cylinder head coke up (under 80k miles, not covered by warranty by BMW)
If my research is correct, you want post 04 to get the modified supercharger, more power as stock and an LSD - but pre 06 to avoid the PSA engine.
Apparently anything post 2010 the VVT issue is sorted in the motor, but they're a bit pricier obviously.
As an aside, the FIAT 595(?) is absolutely lunatic! Sounds great, and is nearly 200bhp in a teeny wheelbase
lots of bargains to be had if you can live with the build quality... Or fit