2015 e-4 Needing new Batteries needed

I have a 2015 e-4 with dead factory batt’s currently installed. The current batteries are Polaris, any suggestions for the best brand/type, and anything not in the manual I might need to know regarding changing them? Thank you.

I have a 2008 GEM e2. It had gel batteries. Last January I purchased and installed Allied Lithium batteries. Plug-n-play installation. Lithium is expensive and also problem free. Not sure what they offer for a newer GEM. Alliedbattery.com