I've found the brushable type is much lower quality than it was some years ago. Even the 3M.

I would not use latex caulk. It is water based and can absorb water even when cured. Not good for use on metal.

Three things I have used that work. Eastwood has a polyurethane seam seal in a caulking tube. It is tough and stays put. A little harder to work with than the brushable type. To smooth and get the brushed appearance I use a disposable paint brush with about half the hairs cut off to make it stiffer. Dip in a little paint thinner and brush soon after application.

Polyurethane caulk from the home improvement store works well.

Butyl rubber caulk from the home improvement store also works well but it takes days/weeks to set up.