It depends a lot on the application, how large is the battery bank, how quickly do you want to recharge it, is it used primarily for dockside maintenance or while at anchor via the genset?
Magnum and MV both make good products, but there are others, (you might consider Victron as well) . Any charger you select should have 'on the battery temperature compensation'. More on chargers here
https://stevedmarineconsulting.com/w...ugust-2014.pdf