I find the fireworks quotient is inversely proportional to the villa number, Rooney, and thus 21 would be a good bet. I would recommend 1-11-14, but don't for the love of god step into the '1' part of 1-11-14 on new year's or you'll wake up in the burns hospital where a surgeon will tell you 'feliz ano nuevo'
NYE in BA is stressful (firework embers falling on your head) and a little boring, since most people get the heck out of town. If you need to be somewhat close by, go to the beach at Pinamar/Carilo, where you can chow down and dance in the sand without third degree burns!
Hiya, good advice so far minus the villa part. I think it all depends what you are looking for. If you are of clubbing age the night clubs are open but usually only get going around 2 am as nYE is a family event first and then an excuse to hit the clubs. We will be doing our lasy minute takers asado (BBQ) on the boat again which was a hit last year. Some hotels also lay on evening entertainment. You definitely will not be without options. But yes it will be loud so if you want a qujeter evening it is a good idea to head out of the city.