Riding and camping Northern California and beyond, since 1965!

I need to replace the main battery on my 2014 GSA. Does anyone have suggestions - best to go with OEM or after-market? Brand suggestions? 

I now live up in Graeagle CA - any club members coming up this way, let me know. I just returned from an 8 week trip to the UK and looking to do a couple of local rides - overnight or day trips.