I have had the same experience, I love Puerto Madero and would not dream of living elsewhere, but know a lot of people say the same about Palermo - both are very different barrios. One new modern, and the other a bit more that neighboorhood feeling - lots of bars and restaurants, and people.
Agree with the list above. My reasons for liking Puerto Madero are my flat has a big pool, gym, I can use the bank at night, and feel safe all the time, its nice and quiet, and there's a huge nature reserve for morning walks/ biking/ jogging - the restaurants are good and its only 15 min walk to the microcentre, all the buses, metro's and san Telmo. And in way of transport its about 20 - 30 pesos in a cab to palermo, which is about 4 dollars. And I like that its not a big expat hang out, I was one of the only European foreigners in our flats - lots of other LATAM expats though. And the best part is crossing the bridge at the end of a crazy day in the city and its just peaceful, quiet and relaxing. I do admit it needs a big supermarket, and if I go out I tend to head over to Palermo - but then enjoy heading home again. Good luck in you decision making ;-)