Both NOrthstar and ODyssey tout their pure Lead thin plate technology, and they have the super high CCA numbers which make them effective as dual purpose batteries. How many deep cycles they sacrifice for those higher CCA numbers is a question for sure.
Lifelines CCA ratings are less as they are designed only for deep cycling, but surely have enough CCA for engine starting too. Lifeline also makes starting batteries.
I'll be sure to let this forum know when my 0.060 thin plate pure Lead AGM battery fails in my deep/shallow cycling, and engine starting usage. At this point in its life is is retaining capacity to an impressive degree. So much so it is my only battery, for both house and engine starting duties and I've never had so much confidence in a battery I've owned. It will be 3 years old in November.
If I wanted a pure Deep cycle AGM, lifeline hands down is the winner in my opinion.
But I like seeing my voltmeter stay above 12 volts when cranking my engine.
This single Northstar-27 at 930CCA,when new, could crank my engine faster than 2 flooded marine 27s at 1300CCA, in parallel could, and it also maintains higher voltage than them during 45AH of discharge.
Batteries plus sells Northstar batteries as X2 power, and adds another year onto the 4 year free replacement warranty.
On my experience with this battery I can recommend them, as long as one can high amp recharge them when cycled deeply. Without the high amp recharge, they will walk down quickly in apparent capacity. Sometimes it takes two back to back high amp recharges from 50% to restore performance.
Since Lifeline and Northstar are about the same, price wise, if the higher CCA is not required for engine starting or high inverter loads, go for Lifeline. They are solid and dependable and pretty much the gold standard of deep cycle AGM.