I'm using all Duracell AGM's purchased at Sam's Club.
Group 34 43.10 lbs. 955 MCA 55 AH. $119.32
Group 24 52.40 lbs. 800 MCA 78 AH. Did not see availability at my store.
Group 27 61.55 lbs. 900 MCA 92 AH. $158.88
Group 31 67.35 lbs. 1,000 MCA 105 AH. $179.74
I used a Group 34M Duracell Marine AGM for my Yamaha F150's. About 9 lbs lighter than a Group 24 and 17 lbs lighter than a Group 27 with higher MCA rating but less capacity. Also used for my 4th battery for bow thruster, windlass and bait tank pumps.
For the house I use a single Group 27 AGM. You could parallel two new ones. Or do a Group 31.
Both engines wired with charging shunts. One connected to house the other to the 4th battery. When underway all 4 batteries are charging.