It's a perfectly viable alternative but it depends on your personal needs. Personally, we don't need 500 shopping channels and find most of sky's original programming to be dull and far from original so we're on BT TV with no extra channels other than the Big Sport package.
For other content we use Netflix, Disney+ etc but thanks to Sky, Disney+ and Discovery+ aren't available on BT TV so you'll also need a streaming stick. But with said stick, you can add the NowTV, BT Sport and various other apps.
We've got 2 Roku's and it gives us complete flexibility when we watch.
Also, should something come on Sky Atlantic, Cinema or Box Sets that you want to watch, you can upgrade your package for a month and then go back down to just the Sports package etc. It is that flexible.
Our. Big Sport is £45 a month which includes an extra £5 for BT Sport Ultimate and the NowTV HD Boost 👌