Silicone caulk is a devil to remove and leaves a residue that hinders re-caulking, and often takes some of the substrate with it when you try to remove it.
It doesn't always seal too well, you find it peeling along the edges.
It discolors easily and is usually not paintable.
For all of these wonderful features it is more expensive.
Oh, it is good for aquariums if you get the right one.