Greasable joints have the advantage of flushing out water if you spend time crossing deep water. Other than that, it come down to preference on sealed or greasable. I have greasable in the front axle u-joints, and not on issue greasing them when doing the other maintenance items on the truck. Have a small grease gun (type used for grease chain saw bars) that I carry in the truck. This is for the few times that I have to cross a small creek on a hunting property.