I've got a Blue and will be getting another for the Sequoia, but if you search the archives you'll see there are better batteries out there. Some will say that Optima is overpriced, as well.
It's like saying Mobil1 is the best oil - it's awesome, but there are better ones.
When someone asks for the 'best boat battery' I'll say Optima, just like I'd answer Mobil1 if asked about oil.
Either choice is a good one, and you can buy both (Optima Blue and Mobil1) at your friendly COSTCO. So easy to get, either one are no-brainers.