@artleyt115, you can take some of these comments about anchoring etiquette with the grain of salt. Some of us have this notion that pristine anchorages populated only by quiet sailors are everywhere and you will stand out like a sore thumb if you play your radio or TV, or heaven forbid, run your generator. Well, maybe if you trailer to some remote lake in the Adirondacks or find yourself in some secluded location on Lake Champlain ... but I really doubt you will be disturbing anyone on Lake Wallenpaupack if you turn up the volume during a summer evening! I'll bet you already have at least a basic sense of etiquette, and you may be a complete delight to be anchored next to for all I know, so you can just dismiss the browbeating over the generator in my opinion.
The simple answer to your question is that your relatively simple needs on an Oday 26 are probably best served by a pair of Group 27 or Group 31 FLA batteries giving you up to 200 ah of capacity. Be sure to measure the location where the batteries will be placed because space is usually an issue. As many say, 6V Golf Cart batts wired in series for 12V and parallel for efficient capacity will provide the most capacity at the most economical price. I've found that 6V golf cart batts are taller than Group 27 batts and therefore on my Starwind 27, I couldn't fit them in the space available.
AGM batteries are far more expensive and may have some advantages over FLA batteries (you can find discussions about the advantages and disadvantages of AGM very easily on the internet) but they have different charging requirements and it will probably cost you more in related expenses to upgrade your charging system. Is it worth it? In your case, probably not. I've read Mainesail's opinion about AGM batteries and he basically says that with the existence & advantages of LiFePO4 batteries, there is really no reason anymore to consider AGM batteries. I just bought an AGM battery for my start/reserve battery, but that's because I have an existing AGM house bank that came with the boat, and my charging system is already set up for it. You'll spend SO much more for LiFePO batts and related systems that I can't even imagine how you could justify the expense based on your simple needs.
So my suggestion is that you purchase the most ah capacity that you can reasonably fit with FLA batteries and be sure to set up a charging system to keep them charged & topped off while you have the boat on a trailer. Use the generator whenever you must ... I suspect there will never be any complaints!
There really is no need to make this too complicated!