I tried my favorites on the cosmo, and so far, the result is that I'm sticking with stock:
1. TSF Launcher - Pretty, great customization for look and feel, but landscape/portrait issues on the Cosmo, with the background wallpaper not orienting or scaling correctly if its a static wallpaper picker.
2. Next Launcher - Constantly crashes.
3. Action Launcher 3 - Fantastic overall, but has orientation issues at lock/unlock. Also randomly has plugins crash.
4. Nova Launcher - wallpaper issues, a little bland
5. Microsoft Launcher - completely fails to work in landscape at this resolution.
I've recently discovered that the cosmo is quite usable at 300dpi, and i may give some of the 3rd party launchers another shot. My main reason for sticking with stock instead of the mostly working action launcher is that android for work integration is far superior on it. "Island" is a must have for me on non samsung devices where I miss the encrypted knox backed private folder. Its a decent alternative, and works nicely on the cosmo, especially in the stock launcher.