Maintenance free batteries which you are naming as sealed batteries are also good.
But personally, I prefer conventional lead acid batteries over maintenance free batteries provided they are properly maintained, are of a good brand, and were charged with proper sp. gravity (acid) at the time of installation.
You shall ensure that the battery wire clamps are of lead and not brass. This is very important as sulfation will take place rapidly due to different nature of material.
Conventional lead acid batteries last longer than maintenance free batteries if properly maintained.