Darrah - we've been through this a few times this year, in Technical section. And every few months in all the previous years, since AGM - or this forum - came into existence. There are benefits to each type, depends on your particular situation.
I have AGM by Chinese UB/UPG. Cost me $180 per 100 AH, 12V. They are cheaper than Deka, Full River or Lifeline (I think these 4 names is all that there is). There are cheaper brands yet, but those I wouldn't even call a "brand",. Flooded 6V cost $140 per 225AH, i.e. per 112 AH. Costco 6V are probably cheaper yet. Cost is not important if you treat your battery right, so it lasts 5 years or more, and your battery bank is not terribly big. You pay $60 or $80 more for AGM once in a while, no big deal. But, if you keep 500 AH bank and throw it away every couple of years, then it adds up quickly.
My reason for AGM was - mostly - the need to keep it stored without charging. Solar system wasn't up yet, so they were just sitting there without maintenance charge for almost a year, losing 40% of charge. You can't do this with flooded, they will discharge down to zero in 4 months, you do this couple of times and then can throw it away.
Also, flooded need watering. They lose water even if you leave them on trickle charge, and in several months could lose a lot.
If and when I move to live in trailer fulltime, there is a good chance that I will get some cheap flooded.
Another reason was - a possible location of batteries inside the trailer, in front pass-through storage. It's accessible from outside, but it's in fact under the bed - you lift the bed and here they are. AGM don't release toxic fumes or explosive hydrogen gas - very rarely, only if you severely overcharge them. It wouldn't be a good idea putting the flooded there.
And there are other differences - important to some people and not important to others.
AGM can take - usually - slightly higher charging current than flooded, and Lifeline AGM can take MUCH higher current.
AGM would keep the voltage better under the load - voltage drops when you apply high loads, and in flooded it drops more than in AGM, some DC devices wouldn't work properly when voltage is too low.
AGM you can't equalize - only Lifeline explains when and how to do this, other manufacturers just tell usual bullchit that AGM you "don't need" to equalize because are maintenance free. I think when my UPG will lose 15-20% of capacity, I will try boiling them at EQ voltage for an hour or so, even if there is nothing in the manual.
