This is like asking what brand oil is best...
Best for the buck?... I will say the Deka ETX9
(its an AGM). But keep in mind, many different companies re-label the Deka (East Penn Manufacturing) battery as their own label. Good news is the Deka has a very certain unique top posts and thats an easy way to spot it.
My OEM battery died on me couple months ago and got mine from Autozone. They generally keep them in stock so if you have a store near you, walk in and get it.