Herb does make a really good point about replaceables, which is why I have (oddly?) felt comfortable with the starting batteries AAA has put in my vehicles when mine suddenly die on the road.
However, I did extensive research when I converted my boat to electric propulsion and came up with Lifeline as the best there is for AGM. Dang, those things have lived through flooding in the bilge and all kinds of stuff. And they just keep on going. They're more expensive than many but, to my mind, incredibly high quality.
As to cost... gee, we have multi-thousand dollar rigs here, so the idea of worrying about fifty or a hundred bucks here or there seems kinda silly to me. But, each has to make his and her own decision about that. Do look into Lifeline reviews, though. They're darn good.
.