Garmin Vivofit HR vs Apple Watch for activity tracking

Right now, I use a Garmin VivoFit HR as an activity tracker and I'm fairly pleased with it, but I've been thinking about an Apple Watch. Are there folks out there using Apple Watches as activity trackers? Do you like it? Did you use something else before? What do you like?

The Vivofit HR seems to do a good job with heart rate and calories. It has a nice app interface. I'm interested to see what folks thinks.

Thanks in advance.