Excellent summary on all counts, thank you

STi is more car than I'm looking for (with higher insurance than I feel like paying also.) Ditto for a used Evo 8. I'm hoping to spend around $18k.
WRX would indeed be very versatile but I don't need 4 doors or AWD for any other reason (I'm keeping the Jeep around for those duties.) I also don't particularly love the look or sound of them.
Cooper S is out of my price range unless I lease it, in which case I can't modify it very much. And I'm not so sure about the long-term reliability with purchasing a slightly used one in my price range. And I'm not a huge fan of FWD. But I consider "kartlike" to be a very good thing.

E36 M3 will require the most maintenance and potentially the highest costs on top of a payment. But I can't think of a better car in that price range for "triple duty." Plus, I've wanted one since they came out.
Maybe a strong running 100k+ mile '95 M3 for around $12k is the answer, and keep the dollar difference around to pay for the long list of "minor" things I'm sure it will need... Real suspension, light wheels, sticky tires, real brakes, rollbar, harnesses, seats, intake, full exhaust, ECU, etc

Thanks again,
Jon