I'm running pro mariner 2& 3 bank chargers now. Only have two years on them so far but they have been fine.
My previous boat went through three of them over 14 years. Corrosion was the culprit. Whatever u get choose a mounting area that stays dry or at least dries out when it does get wet even though they are waterproof. That was my issue before...floor mounting and it never seemed to dry out under the unit. In hind sight I should have elevated some to allow air flow under it.
If you have a separate cranking battery and a 24 volt TM I would highly recommend a 3 bank charger. I have had a 2 bank Dual Pro charger for 20 yrs. I also have a 3 bank Bass Pro model that I have had about 8+ yrs... no issues with either model. Keeping them dry and allowing good air circulation (they can get pretty warm during a hot summer night long charge) are the keys.
I have a Powermania 2 bank that I chose because it is designed to work fine with an extension chord whereas most chargers either won't work correctly or will just burn out on a chord. It is advertised as bringing a dead battery back in 4 hours. I don't doubt it because it will fully charge two that are very low in no more than 6. My boat is set up for 24v trolling and 12v cranking. I fished at night a lot this winter and started running a 4th battery just to run my fish finders because my cranking battery would get really low running those and safety lights for hours without running the big motor. I picked up a Cabela's 2 bank charger and it definitely doesn't charge as quickly as the Powermania.