I haven't seen Stern's glass next to Invisiglass.
I have seen it next to Roman's (AKA PDI).
Stern's has a much more pronounced colour cast, much worse reflection, and also appeared to permit less transmission (pf looked a little darker).
Invisiglass vs Roman's has a different colour cast (greenish vs bluish) though not stronger as per Stern's, reflection quite a bit worse, transmission maybe a tiny bit worse (marginal).
I'd be surprised if Stern's didn't immediately appear worse next to JJP's, per the OP's photo and premise of the thread.
As for people claiming they can see no difference between normal glass and Roman's / PDI (or the others). Well, some people swear blind they can't tell the difference standard glass or acrylic and anti-reflective museum quality stuff in the art world. It's indescribably obvious. They say they can't tell even when you can barely see the painting or poster due to reflection, and there's one next to it with no perceivable reflection until you get close.
Either they're blind / severely lacking in observational skills ... or they've managed to bio-augment their eyes with a polariser.