[Al Skierkiewicz]

Either battery is fine. The MK battery is an AGM while the Enersys is a gelcell. The output characteristics, useful life, max output and amp hour ratings are nearly identical. In addition the batteries are roughly the same weight and the size is standard for this battery type. The difference in rated amp hour is merely a difference in the testing, discharge time vs. terminal voltage. If you compare the graphs for each battery they will overlap.