I like their charisma, can tell you really think a lot of details about them! about the polished part, i think there's always room to evolve in different styles. for example: i noticed your arms move in curved form, that's a chracteristic of style, the more you observe references that uses this style of arm and pay attention to how they move the more you can expand your own style! but be confidant, you put a lot of work in these concepts, your concepts have beautiful colors and each chracter has it's own uniqueness!