King 94 is fantastic. She, along with K' are also part of the current King event bonus team meaning you get more points in her event when running them together. The event gets you some neat items and King's skill card. Outside of that you probably don't need her if you don't like her as you have K' on Red. If the choice is between King or Mai, just go with your heart. Otherwise Yuri to add some greens to your plate. I pulled Yuri yesterday but haven't leveled her yet so can't give feedback.
Also, for purple everyone recommends Shermie and I'm thinking I'll pick her up as well since her Leader Skill is so useful. I often pick her as support just for its perk.