JBL or Polk?

So many variables since both companies have entry, mid, and high end model speakers. Also, most speakers (low , mid range models) are made in China. Amplifiers, speaker positioning, room acoustics all influence speaker sound. If you like the sound of your JBL’s you may want to keep them. Several times I sold stereo equipment, replaced it with other models, and I was disappointed. Auditioning speakers side x side is the best option when comparing brand A vs. brand B

Care to disclose the speakers you are looking at? JBL and Polk both make a very wide range of speakers. If you’re asking about HTIB (home theater in a box) they are all pretty much the same and suck.