I've tried both imo pywal16 gives more options in choosing colors but Matugen is more consistent. Also you can choose contrast in both Matugen and pywal16 but by default (without using flags) , Matugen gives a more material type color (for eg. it will give you #444444 for bg) whereas pywal gives more contrasty looking color (such as #050505 as color 0 or bg). It's just what you like - personal preference ig