Best in the 15k USED range?

Well the Talon I've put so much blood sweat and tears into is pretty darn dead. It runs, and drives, but all the mods and extras might as well be stickers in terms of actual usefulness now (engine needs serious overhaul, and im not wasting money on it). So I'm going shopping for a new ride. I thought I had it pretty well narrowed down in terms of what I liked, but I'm going to throw this one out for debate and to make sure I'm thinking clearly =)
Current 3 prospects
2005 G35 coupe/350z
2005 Mini Cooper S
2005 Mustang GT(or maybe an '04 Mach 1).
Opinions welcome. As well as any others I might be overlooking.
Rules.
1. Within $15k-19k new or used, would like to stay as close to 15k as possible.
2. Decent aftermarket. I tinker with my stuff =)
3. Driving EXPERIENCE is the most important thing. In raw power the Mini doesn't compare, but its FUN to drive, so it rates high.
4. Try not to go older than 03. I don't feel like working on it because it has 200k miles on it. If older than 03 have a good reason.
5. Fire away!