I think most people's opinion is based off of a bad experience with a certain brand for whatever reason. I'm guilty of this myself.
Had an Everstart (Walmart) years ago in a car, and had an Exide deep cycle (Academy) in a boat that didn't last. So, I've stayed away from those 2 brands, while most will say they're good batteries. I probably just got a bad one.
I've had good service from Duralast (Autozone), Interstate, & Advance Auto. Had a Duralast deep cycle that lasted 7 years. Used it as trolling battery. Keeping it charged and maintained is key with any battery.
I personally think the AGMs are not worth the extra price. I've had those too and fished with friends that had them, and a good 29 or 31 group acid deep cycle seems to hold a charge just as long in my experience.