Short black! I know I'm in the minority on that, but those are the ones I put on dh's PV (yes, I do all his filling for him.

)
The clear ones crack no matter what you do with them. Dh has an air-brusher's touch with them and I still wound up trying to get juice out of slots of his PCC. I like dripping, so personally, I vote for a regular sized rebuild-able 510 atty.