Not saying the fiat is bad (i have no exp with it) but I see really no reason to get one of those over a Mini if you're looking at weird cars like this. They are bigger for the city, but still tiny and better than the fiats in every way from the comparisons I've seen. There is a comparo on youtube and the guys take a 2004 base mini over a brand new fiat... S vs Abarth probably widens the gap.
Yes, i own a mini lol.
The "S" sounds like the standard Abarth, the extra 25/30 hp are sold as the esseesse kit originally.
Anyway, where the FIAT is class-leading is in aural pleasure. It really rorts and snorts at you all day (
http://blog.caranddriver.com/name-that-exhaust-note-episode-127/), like the little turbocharged midget it is. Any N/A Mini will not be as much fun, aurally or to drive.
A supercharged one (Cooper S or JCW) will on the other hand be either a lot or a hell of a lot more fun. The JCW puts about the maximum performance on that chassis that it gracefully accepts.
It's tough to make a proper recommendation for me, as I don't know the US market, and the used market even less, but a 1-series, Z3 breadwagon, (R)S3 might also be options, depending on whether you can stomach age/risk/parts.
One of the advantages of the Abarth, is that the body panels are from a FIAT 500, except the bumpers and spoiler, so something like a door should be relatively cheap to replace, considering how many of those go off the lines every day. And so far I've not heard of any major issues with the Euro-Abarths, but then I've not really looked. If I had to get an Abarth, it would be a Punto in any case. Fun fact: that's a GM platform (shared with Corsa VXR/OPC).