Angela is the least to be worried about her awakening or her sig ability among your list. In fact, her sig ability is almost irrelevant. Her damage output has no dependency on the sig level. Medusa on the other hand has alot of dependency not just on being awakened, but also having the right synergy. Others are good to be awakened, but not absolutely must.
While Magik is a "nice to have awakened", fighting an awakened Ultron is a very different experience than unawakened. Especially if your champ has energy based powers (like Dr. Strange).
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Awakening Magik allows you to use her on defense. She's still a beast on attack unawakened.
Ultron doesn't really need to be awakened. All it does is allow you to absorb health from energy attacks. Not a huge benefit.
Angela doesn't need to be awakened at all. She gets slightly better, but not worth an AG.
Medusa needs to be awakened to unlock her furies (and living strands).
I would do Medusa or Magik depending on your needs.