Dicor Self Leveling or Eternabond Tape

Where is it going, what is it sealing ?

This determines what is best

For square roof vents, I prefer Eternabond tape

For round plumbing vents, use some clay or something to make a little coffer dam, around the vent then poor in the Dicor
Self leveling will flatten out and run down hill, so you must be level and have a way to maintain thickness

I'm not real fond of the self leveling caulk, unless I'm trying to fill a crack in a roof seam

I really prefer regular thick caulking that stays where I put it