I personally like Roederstein, Rifa and Wima polypropylene MKP series. They're all very similar in sound and quality. And the TRW 363 series polypropylenes aren't bad either. With the dielectric constant between polyproplyene and Teflon™ being so close, I really can't hear the difference.What do you think about the Vishay (ERO) Roederstein capacitors in different application on tube amplifier?