I had more or less abandoned glass screw-in filters due to the number of different sizes needed. I have Hoya, B+W, Tiffen, Heliopan, Zeiss, Leitz, Voigtländer and a few others. And Cokin (both A and P sizes) and Lee...

Some films give strange colours with Cokin "neutral" filters, but it varies with the film too. That's why I bought a Lee holder and two Grads. And a B&W set, and a IR filter. And then I decided to use 35mm IR film, and bought a Heliopan filter. Mostly because a Lee filter holder would look ridiculous on a 21mm Color-Skopar lens

But the Heliopan screw-ins are great, no doubt about it. The mechanical quality is way beyond anything else I've seen!