My favorites tend to be the ones I wrote! :) (but I'll use NoFrills, Actiface, Line, and a few more at times)
If you're new to Garmin or Connect IQ, keep in mind that many watchfaces also allow for custom settings (from your phone or Garmin Express), where you can change what's displayed, colors, etc.
I tend to use analog watchfaces. I used Time Flies a while and loved how customizable it was but I wasn't able to achieve clean enough chronograph look. I switched to Steam Gauge which looks really good although there is limited customization options and no second hand (which I don't require). By the way, there is a manual in the developer's website to Time Flies and it's good to browse through it if you cannot achieve something on your own.
