I actually use both Printfile and Glassine. (Also had the unfortunate experience of using some "non-archival" plastic ones - ouch! They started to eat into my B&W negs something awful!)
Printfile were extremely difficult to lay my hands on (20 years ago) and quite expensive to import, hence my using Glassine as well. But I give two thumbs up for either - they are both great products.