I've used real Kapton polyimide (lots and lots) and cheap knock-off stuff. Both worked; the real stuff held better under reflow temperatures than the knock-off brand did (not a big surprise, there). Same goes for the glue on copper tape: 3M has some of the best adhesives around, so their tape is pricey but always works and holds for the long-term. The knock-off stuff MOSTLY works.
I've run out of the roll of true Dupont Kapton I had, so all I have left here at home is the knock-off stuff. It's still working OK for me.
One of the benefits of using the true name-brand: Dupont offers Kapton in a low-ESD version, and I haven't seen anything similar from China. You can find the tech sheet at kaptontape.com I verified at work that it's truly less than 50V charge when you pull a strip off of the roll. I've clocked other tapes in excess of 2000V worth of charge. Fun experiment: grab a roll of Scotch Magic Transparent tape, go into the bathroom with a fluorescent bulb, and set the roll of tape against the fluorescent bulb. Turn the light off, and peel off a strip of the tape. The fluorescent bulb will light weakly. That's some SERIOUS static charge there. We only allow low-ESD tapes in our sensitive ESD Protected Areas.