No one is forcing you to use their modem or router.

Out on the west coast I’ve generally been fine with spectrum modulo the upload speed although they’ve did a recent upgrade to 100mbit/s+ due to new DOCSIS standards. I finally got Fiber in SF so I switched but Spectrum was finally kind of good enough for the most part.

At the apartment I lived at until last year, Spectrum only offered up to half a gig down unless you used their modem (which of course meant an extra $15 per month on top of the plan for a full gig already being more expensive). Of course, neither of these were symmetric, with the connection listed as "mixed" between copper and fiber. I stuck with the half gig since it was the best option without paying them for the "privilege" of using their equipment.

At my house now we get 2 gigs up and down with fiber from Optimum for cheaper than the plan we had from Spectrum. We've had maybe two hours of downtime total from outages in 16-17 months, compared to probably 4-5x as much in the same period on average from Spectrum. Some providers really do just suck.