I've got a G Watch, Moto 360, and Apple Watch. The bit about the UI is interesting - IMHO, Apple's launcher and glance mechanism is much nicer than Android Wear, but Android Wear's notifications and watchfaces are a lot prettier than the Apple Watch. I also think that Android Wear feels more integrated as a UI; it feels like Apple put a whole lot of effort into the stock apps, but their notifications are a kludgy afterthought.

I'm using the Apple Watch as my primary smartwatch right now, largely because I think the hardware is better, but I've got the Android watches charging on the shelf and thought it was pretty ironic to see a Google product be prettier than an Apple one but less practical.