I'm with DaveB in that I haven't really had a real need for apps on my watch as the phone has always been better for that function. There's a couple of things I do find useful, Keep and Authenticator, but otherwise not too much else. I have the LG G Watch, and while it's aged I have never really been able to convince myself it needs replacing. I think it comes down to what you want it to do for you, I get notifications, control music(play music)/video(plex) and occasionally use the voice commands for messaging. The quick replies and call control come in handy too. 

I came across from the Pebble Steel, like michaelmurfy and while I missed the physical controls which are easier for traffic light song changes on the motorcycle, overall the notifications and simple quick controls I find myself preferring AndroidWear. A replacement for me would be entirely based on the appearance of the device, I'm not too worried in upgrading for cellular or GPS connectivity, and I think the Gear S2 looks great. I would be nervous about Tizen, but probably for no other reason than Google is more widespread, and I know this doesn't really mean a lot. The G Watch gets through a day easily and is still running 6.0.1 nicely 22 months later, will the S2 be the same, probably.

If it was me, and I had to pick between the two, I'd go for Android wear, just for the Google support, but a close second consideration would be whether I liked the look of the watch on my wrist, as essentially, both will tell me the time and my notifications.