Pretty much any 6* will Black B is always well liked Alpina can be an amazing power piece

I picked my 3 because

1 - Speed team +150 speed will be amazing
2 - Victoria - good skills fun little piece
3 - Acacia - just really loved the way she behaved and another all attack skill and Ok powers

I'm beyond the point where total power greatly matters - 2 slices was, in retrospect, a poor choice one way should have grabbed a pierce - but this is about the heart not the head - also now 13 rainbows (well 12 and the free one) and 3 5* of near 6* level (well - one is amped to the max to get there)