Root is a requirement. New rom? I don't know. Phones are inherently spy devices, and you won't get away from that, even with a fully libre rom(which is as rare as unicorns, and still has caveats). Most roms are proprietary, so I'm not sure trading one master for another makes a lot sense.
You need to accept you're being spied on, and mitigate it as best you can. That can be done well enough with root, and you'll retain the special sauce that works well with your phone's hardware.
Mobile devices are irritating and restrictive. People willingly give up their rights for trivial convenience, and companies willingly take them. I was constrained to using Sprint due to a company account. If I were choosing on my own, I'd pick a service/phone that gave the most freedom in use. None that I'm aware of are great, but some are better than others. Sprint's on the better side of the scale, but I don't know if they're the best.