I tried both Spectrum and Frontier at 1Gbit/s. I'm in Santa Monica. Only one example but:

Frontier was so much better than Spectrum — pings to 8.8.8.8 are consistently 6-8ms, compared to Spectrum at 10-30ms. And Frontier download speeds are 500Mbps-800Mbps, significantly higher than Spectrum.

The installation was also more competent and organized.

I'd guess there's lots of regional variation though.