First I would recommend Replacing all the batteries at the same time. Engine, Thruster? and House. Doing this keeps the battery replacement in a cycle.Next decide what type of battery you want to use. Wet, maintenance free, or AGM. Using the same battery type for all battery banks so the charger can charge the battery type correctly.
I had maintenance free Centennial Fluid Motion installed batteries. Cheap batteries that lasted 3 seasons. Advantages to theses batteries inexpensive, weighed under 50 lbs, The thruster and house were DP (dual purpose) and the engine battery was a cranking battery ( higher CCA). The DP batteries were 92 AH. I had no solar panel, charging was done either by shore power or engine. I had a 2000W inverter that I could use electric stove top, Microwave, outlets (air drier),and keep the 12V refrigerator operating 24/7 when cruising and on the hook. This all was done with conservative power management and in the morning required the main engine or portable generator to run to recharge the battery bank after a 12 to 15 hour period of time. I did install a parallel switch between the house and thruster battery so I could use the thruster battery as a addition house bank resource.
When the Centennial batteries were no longer able to hold a charge properly I decided to go with AGM. My thought was the known quicker charge capabilities, maintenance free, higher number of charging cycles. The AH capacity stayed the same (Group 27) 92AH, The weight increased a lot, 20lbs per battery, 80lbs more in the stern of a weight sensitive 8'6" beam boat. Believe me this did not go unnoticed when I launched the boat. The batteries I chose where Northstar AGM, made in USA, well made, very good reviews and PRICY. $1150.00 for four batteries. Were they with it? I installed them in 2019, and the performance of the batteries has not changed. They hold a good charge. So to early to tell. If the batteries maintain that for 3 more years it may be close to break even.
If I were to do it again. I would have installed Deka (East Penn manufacturing) 27M6 engine cranking battery 850CCA - 1050 MCA, DC27 House and thruster batteries 575CCA - 705 MCA, 90AH , weight 27M6 53lbs, DC27 53lbs. The batteries described are no frills inexpensive 3 year batteries that will perform well for the average 30' or smaller boat. 4 of theses batteries can be purchased for under $500.00. If I got three years of service from theses batteries in six years I would have spent $
1000.00 on batteries. With theses batteries I'm getting close to the same needed capacity and 70lbs lighter.
There are plenty of good batteries on the market. I choose Deka because I have used them for many years and always got good service from them. Made in USA.