I researched a lot and found that the most bang for the buck was at Batteries Plus. I bought the 6V 230AH. They also have 10% off if you buy online but they also give you the 10% in store if you ask for it. Find some old cores to bring along as the core charge is steep.
I also go by weight and these are heavier (more lead) than the Comparable Trojan T-105 and more AH. You can get a 235AH for a few bucks more but in the long run 5AH more won't make a difference.
https://www.batteriesplus.com/productdetails/sligc115