I recommend phlojel, but I don't have any experience with penetrate (so i can't really speak)
Basically the smaller the molecule you attempt to use transdermally the better it will work. So Tren base would be ideal.
Basically the only reason one would use an ester would be because you were using cattle pellets or you just had a butt load of powder left over from home brew.
Tren Ace will work though in a pinch.
From the research I have read, most of the esters are lost in the transdermal absorbtion process, so all you really get systematically is the base hormone anyway. Applications are 2x a day so the ester is pointless.