I own a Mini Cooper S
My Dad owns a Mini Cooper S with the Works Package
My Mom owns a Mini Cooper with automatic.
Mini Cooper with Auto: Suprisingly spunky but I can't stand the automatic. Ride is pretty close to the smoothness of a Civic but corners much better.
Mini Cooper S: Fairly powerful engine (163 Hp) but feels like it has gobs of torque. Power is pretty much immediate but really kicks in at around 3200rpm. Corners like a skateboard. Ride is pretty forgiving on highways and a bit rough on bad secondaries. I drive in and around Cleveland Ohio about 100 miles per workday. The seats are very comfortable and supportive even under punishing conditions. I won't lie, on very rough roads and potholes, it can be very annoying (but you usually aren't on those types of roads for very long anyway.....even in Cleveland

). I have a '70 Chevelle with a lighly modified 350 in it and this car 'feels' like it has more torque and will run with the Chevelle in a straight line all day. Cornering is another story though

.
Mini Cooper S JCW package: Truthfully, I think this is a huge waste of money. Is it quicker than the 'S'...yes. Is it more powerful than the 'S'...yes. Does it 'FEEL' like it is faster than the 'S'....NO. The 'S' feels like it has more torque for some reason. The ride is rougher due solely to the larger wheels and shorter rubber. I believe all other suspension is the same (I may be wrong but it doesn't FEEL any different). All other interior items are basically the same.
Conclusion (also just my OPINION):
I drive my cars like I stole them. In other words....I drive them hard. I have had many sessions in all 3 of these cars as we like to 'borrow' each other's cars so this is NOT based on very short stints in each.
I think the base Mini is great for women or guys who could care less about extra power, stoplight action, hitting 90+ mph before leaving the on-ramps (

), or attitude. They are a great values, solidly built and decent on fuel.
I think the Mini Cooper S is the best value for the money. You can rip the tires all you want, you have 6 speeds and a supercharger (NOT a turbo), you have attitude in the stripes and a nice size hood scoop, and this thing will take corners HARD (Power sliding through corners is almost impossible).
I think the Mini Cooper S with the JCW package (Works Ed.) is simply a waste of money. The only real differences are the JCW badges (one on the front hidden in the bottom of the front spoiler and one on the back), the exhaust system (which doesn't sound much different than the stock 'S'), and the extra 35 hp. All this for the low, low price of an additional $5000 PLUS dealer install!
I know that not everybody will agree with these opinions but I do hope they will aid you in your decision.
SDC
Cliff Notes
Mini (with Automatic): Spunky and a good value for non-power hungry people
Mini Cooper S: Great value, great power, great attitude, comfortable.
Mini Cooper S JCW: Great power but not worth the extra $5000+