If I remember from your previous thread you have a Series 3 watch. Although older this is a model that Apple still sell so it might be worth checking if it’s still under warranty, or doing a factory reset to see if this improves things.
Otherwise if it is an upgrade you fancy, it depends if you need the new features, the main being an ECG heart checker (I’m no doctor so not entirely sure how much of a benefit this is) and blood oxygen checker.
If you’re into exercise this might be handy, if you just use it for basic step tracking, notifications etc it might not be a huge requirement
Apple sell the Watch SE which is quite powerful and still pretty up to date, but not too expensive relatively speaking either.
As for the cellular versions - these are a) more expensive and b) require a seperate contract to your main phone. Personally I don’t see much benefit with these.
If you often find yourself with your watch on but your phone nowhere near by this might be helpful but if you are always close to your phone, it shouldn’t make a difference - if you’re doing exercise such as swimming where the phone can’t connect to the watch because it’s far away it will still continue to track your movement.