If everything was working fine on macOS 10.14 and iOS 12 why switch to Linux? I'm sure Android and Linux have their own issues even if they're different from Apple's. Better the devil you know than the devil you don't.
I usually have a look at the macosbeta reddit around the time of the GM release. If there's tons of reported bugs (and there absolutely were this time around, the place was overflowing in bug reports for the latest beta), then I just ignore the new upgrade for ~half a year.
They still push out security fixes for the older OS. And lets face it, the latest versions have been quite underwhelming, you don't miss out on much.
Especially important if the mac in question is your daily money maker. Why waste time, stress and tears (from email corruption) for a few new emojis?
This is the answer. I do IT consulting and support for Apple-based small businesses, and I constantly have to remind my clients to not just accept every update prompt they see. I advise waiting for .1 or .2 releases. There is never a reason to update right away, in my experience.
I'm having a ton of wifi connectivity issues/bluetooth issues/mail/a bunch of other issues and regret upgrading.
There's no need for latest and greatest unless there's something that is 100% crucial that the new update brings.
Honestly I'm thinking of downgrading if I had the time to do so.
That would be fine, but what about the situation where you have no choice? (i.e. buying new hardware or unrelated hardware - there's no excuse for forcing an os upgrade when you buy a new iphone for example.) Try buying a latest model and enjoy being forced to upgrade your laptop os so it can "connect".
Obviously apply security patches regularly.