It sure can get confusing and when seeking opinions, well........
Knowledge is power. In this case, the power to choose the applicable battery for your car. I used to be a route battery salesman for Douglas Battery. They have since closed/sold out their auto battery business. I learned that there were only 4 actual battery manufacturers in the US (Douglas being one of them at the time). However, they manufactured batteries for assorted customers by simply adding their logo and labels. For example, it may have been a Douglas made battery with the NAPA label. So you would think you were getting a NAPA brand battery (which you were, brand wise), but you were getting a Douglas manufactured battery. That said, you may pay more for the NAPA branded battery versus going to the competitor and buying a cheaper Douglas branded, Douglas battery. I never heard of a Douglas battery, but certainly knew the NAPA name and brand. So which one do you think I bought all the time?
Battery Manufacturers and their Battery Brands:
Delphi - AC Delco and some EverStart;
Exide - Champion, Exide, Napa, and some EverStart; and
Johnson Controls Industries - Diehard (Sears), Duralast (AutoZone), Interstate, Kirkland (Costco), Motorcraft (Ford), and some EverStart.
Johnson Controls Industries - Optima brand - Gel cells.
Prices on batteries are absurd. Why? Because they can. And one store rapes you more than another - but you don't know it is made by the same manufacturer because we often buy by brand name because we have been schooled and groomed to trust "brand names."
I buy from Walmart. Better pricing and I have not had any problem. However, here is what I look for: Date coding. There is a sticker on the battery having a letter/number. The letter typically corresponds to the month A=January, B=February, etc.. (They don't generally use "I") The Number is typically the year. 5=2015, 6=2016, 7=2017.
One of the reasons I like Walmart is that I can pull the battery I want, then check the date code so I know I am getting a recent or "fresh" battery - within 6 months at the time I am going to purchase a battery for my car. Go to a store that has them behind the counter, they may not sell a lot of batteries and here it is May 2017, they plop a battery down on the counter that says A/6. I don't want a battery that has been on a shelf over a year. The charge has probably run down or they have put a charge into it to maintain a charge. It'll start your car, but you have technically lost some time/use of the batteries life because the acids in the battery are still working on the lead plates inside. So I make sure I get a "fresh" battery and have refused the old ones - leaving me looking like an ass in front of the clerk who doesn't understand my reasoning or has to get another battery having a newer date code until I say "OK." A good battery salesman/supplier rotates out the batteries as they get older (usually because they were not selling) and replenishes with contemporary dated batteries within 6 months or less.
Do the batteries get tossed? Heck, no. We used to bring them back to the shop and then put them on an industrial slow battery charger (no, not like the one we all use at home) and slowly bring the charge back up on the battery, test it, and then place a new date sticker on it. Fast charging can harm the life of a battery, so the manner in which we re-charged the battery brought it right up to new again and no real deterioration for long life. If the battery was not a big seller, a good salesman would then drop the inventory for the customer so that too many of them did not sit on the shelf, and lose charge - only makes sense.
OK, so date codes are what I look at first. Next, once you know the size of the battery (what Group, as it is called), I simply go for the largest Cranking Amps (CA). More CA's means more lead plates which also mean the heavier the battery within the Group size you need for your car. You never want to go lower than the manufacturer's CA rating for your car, but with most of us tweaking our engines or adding electrical upgrades and the like, I simply shoot for the battery with the highest CA available for that Group size and be done with it, no guessing needed.
I am not too concerned with Cold Cranking Amps (CCA) as I don't live in a region where it gets that cold for long stretches and most of us don't drive our collector cars year round or in below freezing conditions. As the CA of the battery goes up, so does the CCA rating.
I can't speak on the Optima gel batteries as I have never used one. We have customers who insist on them for the battery operated lift gates found on the back of the big truck type trailers used in deliveries. I don't know if it is due to longevity in their use on these trailers or simply the "maintenance free" promotion these batteries claim. From what I have read, you won't get any fumes leaking out or the spilling of acids, so this is probably a big plus for those guys who put the battery in the trunk and would normally have to place it in a battery box that has the acid fumes exhaust tube exiting through the trunk floor.
Warranty. I don't usually care about the warranty. Generally, if your electrical system is good, the battery holds up past its warranty. If you don't have a good alternator that keeps up with your electrical needs, then your battery will degrade. Not a battery problem, but incorrect amp rating for your set-up. So purchasing a battery based on warranty is in my opinion, not a reason to buy it. Generally, the warranty is not a full replacement, but "pro-rated" based on the date of purchase and how much of the batteries life under warranty you used up. So you might pay more for that 5-year battery warranty, and then when it quits on you 4 years later, and the clerk tells you you have $8.73 credited to you under warranty on your next battery. Big whoop! And you paid 1 1/2 times the cost of the same battery that Walmart sells thinking the 5 year warranty was a much better deal than the 3 year warranty. It's their way of making you come back to their store with your dead battery so they can sell you another one from their store. But the $8.73 you get back is nothing because in 4 years, the battery price went up $20.00! Tell me I'm wrong.
And remember, the two batteries may have actually been manufactured by the same battery maker. So what did you really pay extra for?
And that is how I choose a battery.