I am a LONG time WearOS user and fan but I will boldly say: Galaxy Watch is currently the best Smartwatch for Android. Period. And this is from someone who never wanted to give Tizen the time of the day.
Some quick takes...
Initiating texts from messaging apps isn't a show stopper. Android Messages, Facebook Messenger, Allo, Skype all let me respond to messages in a multitude of ways.
I've gotten 3 solid days with sleep tracking on my 46mm model.
Notification's have been rock solid and I don't think I've missed a single one.
Health Tracking seems robust enough and there are lot of options and trackers.
The loss of third party integrations (connected apps) is coming to and end Sept. 1st, so that is something to consider if you need that.
Watch "Apps" don't matter much. I rarely used Google Maps, FB Messenger (which really didn't work), Nest, etc. on WearOS. Inherent apps, integrations and health options seem to work very on the GW.
I'm still hopeful WearOS does something big this fall and an amazing watch is to follow but it is hard to argue about how good the Galaxy Watch is.