I'll just talk about the ones I've driven.
If you get the 500, get the Abarth. Not just because it's Veeky Forums and we're all about fun, but because the engine and trans are more reliable than the standard ones the 500 comes with. Abarth or bust on the Fiat, imo. Also, so so so much fun to toss the Abarth around.
The Cooper is neat, but I've heard bad things about the reliability post-warranty. That said, my dad has one that is well past warranty, and he has had no issues so far, he just maintains it and it keeps running. Great gas mileage, good on roadtrips and in town, the sport mode makes it even more go-kart-y.
Fortwo: It's RR, it weighs nothing, and should have enough power to move it. It should be good, right? But it isn't. It's awful to drive for some reason, it's overpriced, and the interior is the worst out of everything you have in that image.