@TheNobody: see the above post. She has two armour which let her fly, three if her flight armour actually lets her fly or just move really fast and jump high.
@321zigzag1: You're right about the Jupiter cannon thing being around city block buster level. I was more referring to the lacrima that Laxus placed around the city. They were said to be able to destroy the entire town and Erza took out 200 of them by herself. Not really indicative of her being able to tank town buster damage but it definitely showed that she has some crazy durability.
Like I just said she her battle intelligence is very high, like say Natsu, Naruto or Goku. She can easily find out what weaknesses her opponent has and she can formulate a strategy on how to best defeat them. In terms of battle intelligence I place her above Deidara who is shown to sometimes make mistakes during battle and get caught out because of them. Deidara has effectively died twice.
Speed wise I put her above Deidara as well because of her flight armour.
The only threat that I see here is Deidara using C3 but that can be avoided or she could possibly use Flame Empress armour to reduce the flame damage by half. Just a theory but I'm sure she'd find away.
In terms of Deidara flying which seems to be the winning factor for Deidara here, Erza has her black wing armour with which she can also fly if needed and as I stated before she can fire sword pressure blasts like Sephiroth which can cut through steel. She can also fly with her Heaven's wheel armour.