I too preferred Pactra. Mainly for the colors and also it was a few cents cheaper than Testors. Cents were important back then because I also had a comic book budget! To put this in perspective comics were 12 cents new and 5 cents used at a local used book store.
About 6 years ago I went through all my old Testors and Pactra enamel paint bottles (from the 60’s) and trashed all the ones that were dried out or had the consistency of putty. A good 85% of the ones I trashed were Pactra… That percentage suggests it was the paint and not some other factor.
I miss Pactra as well. They had a Dark Olive Drab that was perfect for Vietnam era US AFVs, a superb Metallic Gray/Gun Metal color and several others in their 'namel line. Their International Colors line had some great colors that I really miss as well. One they lablled as “suntan” was perfect for the faded olive green of US uniforms, and their Khaki was perfect shade with just the right hint of yellow in there. Yes, Testors F’ed over all us modelers when they gobbled up and discontinued all their US based competition. So much for anti monopoly laws here. Thier quality control is poor nowadays, and while they do have a nice wide selection of colors available, I would much rather have the option of choosing between brands for all my needs. All I know is that nowadays if I have a choice for a color between Testors or Humbrol in enamels, I will opt for Humbrol in most every case.