I've been trying both the LG G Watch and the Samsung Gear Live for the last couple of days. They offer pretty much the same software experience, the main difference is the Samsung model offers slightly more stylish watch/wallpaper designs although that's a matter of taste. The hardware is where the main differences are, and illustrate the different approach the two companies have.
The Samsung does look slick, the chromed surround is a little too ostentatious for me but I got used to it after a while. It also has a beautifully crisp and bright SuperAMOLED screen which they show off with some colourful watch designs. The superior screen comes at a cost; the battery life is noticeably worse than the LG.
The watch strap on the Gear Live doesn't lie flat, so when not on your wrist the device rests on the chrome surround - which is going to get covered in scratches very quickly. The charging dock is terrible, it clips on to the back of the watch clumsily and feels cheap. Gear Live also has a heart-rate sensor which is a bit of a gimmick, the results were sometimes inconsistent with mutiple readings in series giving a large range of results.
The LG is more understated but it feels like more thought went into the user experience. The body is a simple black rectangle which gives it a prototype feel but I feel less of an idiot wearing it. The strap allows the watch to lie flat on the recharge dock which has a good weight with a rubber base, the watch snaps on magnetically, much better than the Samsung. The screen is not great (blacks appear grey and gradients look stepped) but it does mean the LG has a much better battery life.
Whichever model you choose Android Wear itself is fantastic, the UI is easy to navigate and the speech recognition seems to have improved hugely since Google Now first appeared, even with a Manchester accent I've been replying to text messages without touching my phone - it feels like the future.
The API for developers is very simple (which is a relief after what Google released for Chromecast), existing apps can add support for Google Wear with just a few changes to classes that handle notifications. I've got an app in the works called Milestone that simply tells you how far you've travelled with an additional vibration alert every time you pass another mile or kilometre - it's for when I'm out cycling to give quick and easy feedback on how far I've gone, Android Wear support has been really easy to add.