[Christ]

Latex caulk works well on painted surfaces, and slicks clean.

Silly-Cone works great, too.

Never use Urethane. It gets rock hard.

Silly-Cone stays flexible, but goes through wicked heating/cooling cycles, and will separate if not prepped properly.

Latex cracks if you apply it too thick.

Any "gap" more than 3/8" deep needs something as a backer to create a proper 3-sided seal, or the caulk will eventually fail (way before it's supposed to).