I'm using CMF Watch 3 Pro with Nothing Phone (1) , I had plenty problems with connectivity with the past firmwares, the latest one 1.0.1.70 seems to fix most of the connectivity issues. The assistant and GPT still are hopeless and it's still way better to just shout to the phone than have to deal wit the watch. Anyways the bare essentials work fine now.
I don't really care about battery life I have most of the monitoring on and charge it usually once a couple of days before the sleep (trying not to go below 40% and above 80%). I have it on my wrist all the time when it's not charging.
It's hard to compare the battery life of fitness tracking watches because you have to use two watches at the same time doing the same things on both at the same time. Also things like AOD wrist wakeups and the amount of excersise you do play crucial role in battery life.
So just like that I charge it a bit in the evenings if it's below 50% or If i'm going away for a couple of days I charge it to 100% and leave the charging cable at home.