Cyanogen is great on some devices, not ported as well onto others.
There are dozens of alternatives to mobile Android/iOS/Windows. But not all of them are available for all mobile devices. If you have a particular device then you have a limited selection of firmware/OS options. If you want a particular open OS then you have a limited selection of devices which will support it. So your choices aren't as overwhelming as they might seem at first glance.
Device rooting is still a fairly good option. You can't fully de-google (or de-Apple or de-Microsoft) your gizmo but you can gain control/audit over the most invasive and pervasive features. The problem is embedded code blobs, proprietary instructions running in "black box" logic circuits, you'll never get away from that unless you can fully lobotomize your device at the component level, install an electrical DIP switch across your antennae wires, etc.
Thanks for weighing @Korth. The link you sent seemed to paint a picture that it's still early days in the competitive arena for a truly market-ready alternative to the Android/iOS giants. But, the link also led to:
Apparently google-free with no bloatware welded into it.
Warning about "beta" and "many bugs" don't exactly inspire confidence, but I'm sure these alternative systems will mature soon enough. Luckily, I'm not in panic/paranoid mode about this whole de-google notion and I'm taking precautions with the tools and behaviors I've got for the time being.
Another thing to consider is performance. It's often hard to get real facts. Most people don't run (or at least don't publish) methodical before-vs-after benchmark comparisons. Few devs honestly admit that their code isn't as fast and clever and efficient as code from their competitors. Proponents sing endless praise, opponents hurl endless vitriol, it's hard to find accurate unbiased information which offers an impartial final decision to the end user. There are always decisions and tradeoffs in complex software design, "optimizing" more something vs less something else.
OEMs increasingly build their devices to be reliant on "black box" firmcode, drivers, and APIs. They want to advertise as much "open" and "unlocked" stuff as they can while controlling and securing as much stuff as they can. They have to comply with legal and regulatory mandates in the markets they intend to sell. And, truth be told, they all want to make more money but they are not all entirely corrupt nor entirely evil.
So OS builds which remove or replace software bloat will tend to get better performance, while OS builds which emulate functions embedded in hardware or firmware will tend to actually diminish native performance.
And, as usual, the harder they try to sell it the less you need to buy it (even when it's free). If there's too much focus on new features new features new features then I move along and keep searching for something which doesn't shovel new cargo on top of a wobbly wheel.
If you need to run a specific app then you're basically locked into whatever specific platforms and specific operating systems will support that specific app.
Support resources are also a good indicator of professionalism and quality. If the modded OS is a one-man project then it's not going to be as avidly developed as a popular project with funding and community and wikis and support channels and teams or hierarchies of "volunteer" developers.
I have done some of the same things to my windows laptop before it broke. And since I’m poor I couldn’t afford anything more then a chrome book Laughing out loud.