I have made both and each has its charms and challenges. The older PSI kits had a spring that was about 1/2 inch long. It would occasionally slip down into the tube when you pushed the seam ripper in and would be lost. Now that they have the longer springs - about 1", I like them better. The PSI kits seem to have more options, too - seam ripper (2 sizes), needle threader, stiletto. Just made a pair last week with both sizes of seam rippers, a needle threader, and a stiletto for a cousin.
I had no tried Drewby's suggestion on the ones with the O-ring but definitely will. Instead, I bought replacement O-rings and fixed the ones that wore out. I think the O-rings give a more positive feel when they are seated than the springs do, but for a guy with fat fingers then can be a challenge to install.