I use the stainless whistle tip drip tips. Personally, I like them. My only hangup with them is that sometimes the liquid will gather in the tip instead of dropping straight down. Not sure why this happens, though I find that giving each drop about 1" to fall gives it the velocity to "punch
through. On the rare occasion that it does happen, I find that by tapping my PV (right side up) onto a firm surface (tapping gently with the back end of battery) drops the
juice down. Then, a quick blow into the mouthpiece and I'm ready to go.
Overall, I like mine. They last a good long time, just remember to clean them on a regular basis so they don't get cruddy.
Peace!