I allowed my students time to explore both apps. Then they chose the app they preferred and worked together in groups of 3-4 to build something meaningful with a set of Lego.
All the groups chose My Create. In general they thought both apps were easy to use but they thought My Create had a few extra options not available in Koma Koma. They suggested that Koma Koma would be a good app for K and 1st grade.