how are your battery's wired? do you have an isolater or they hooked up parallel?
if parallel you should get 2 new batts of the same kind. if you have an isolater in there, run whatever you want.
in parallel putting a new batt against an old one, the new one will always compensate for the old one and cause it to run hot or overheat.
i have dual batts in my truck, parallel wired with a shut-off on 1 batt for when the camper is on.
and i currently need new batts myself.
had Optima's on there, normal service (8yrs), but super expensive (need 2...
)
last time i just used 2 wallymart rv/marine batts and i got 9 yrs out of them.
for that length of service and price, you know where my new batts are coming from, don't need to drop huge bucks on a supercalifragilistic brand, horribly overpriced when i can get the same or better life for cheaper