IQI I2 / Kingwear KW88 / (clones)
Big Launcher Wearable (link)
Big Launcher Big Notifications (link)
UCCW (link)
UCCW custom faces already available (link)
Another option is Zooper Widget. While it does support more complex functions, it requires you code analog faces by hand.
PROs
Supports stock widgets and custom widgets
Smartwatch friendly UI
Show more apps than stock
Less mucking about than Nova Launcher and other launcher suggestions so far
Face designers can monetize and protect their work (link)
Faces can have hotspot shortcuts
No custom face limit
Custom icon packs
Large font east to read SMS and phone option
Almost no setup beyond adding screens and setting widgets/shortcuts (so just like what you do on your phone)
Can make custom faces ON THE WATCH! (I’ll release a couple templates ideal for the watches)
Auto weather updating (user selectable time frames)
Celsius AND Fahrenheit option
Next alarm, next event in agenda, and other data points
Calls, SMS, Email and other counters on the face
Tasker support
(I know I’m forgetting other things)
CONs
Faces and widgets are not full screen (can’t be fixed at this time but is still usable)
Changing faces requires going into launcher settings
Faces cannot have seconds, steps or HR
Power button does not turn off display (you just have to wait the 15 seconds)
Costs a whopping $2 for the launcher