I rolled Sophie early and she is near useless for a long time as a starting player. But when she gets awakened - wow! She will be useful later as a very strong lightning rod, hard multiple hitting ganker and her passive heal is handy on poison and desert maps. That said she is not vital all the time.

If you want something to help from the start Despara is excellent. I had one on a previous account and as a main witch she's nuts. I picked up Despara recently and have her at 50CC80 and she outperforms awakened L50 platinum witches. I also have Adele whose Awakened ability is nuts but if I didn't Despara would be my main witch.

In the end having any black early on is good based on raw stats alone. I wouldn't waste time rolling and just pick one of the above.