I would look for the most time in minutes the battery will produce 6VDC @25AMPS and which one is the heaviest... Then cost would be the last thing I would at...
CROWN CR235 6VDC GC2 Battery Specs
CROWN CR235 SpecsTROJAN T105 6VDC GC2 Battery Specs
TROJAN T105 SpecsThe problem with these two batteries is the Crown is a 235AH battery and the Trojan is a 225AH battery. The specs are different.
The Crown will produce 6VDC@25 amps for 459 minutes and weighs 63lbs
The Trojan will produce 6VDC@25 amps for 447 Minutes and weighs 62lbs
Roy Ken