I tend to hear that Duralast is typically the better choice. Just make sure you buy it new. I know that at Autozone you get a lifetime warranty with a new one. I'd assume that other big auto parts stores would do the same as well. I don't know much about Bosch's alternators, but I wouldn't be too worried with them. As for the serpentine belt, I think you'd be better off doing it. It's cheap and better to get it over with while messing with the alternator.