Scenario 1 might go to Mr. 5. Deidara's flight being restricted is huge. He relies on it to dash away from his own explosions or be out of their range in the first place. He couldn't use any decent explosions whereas Mr 5 can easily snipe him with his small explosions. Scenario 2, Deidara by a landslide.
Deidara is odd. Unlike Haku who is the only in the series to do actual multiple one hand seals, Deidara managed to do an hide under the earth technique, a shadow clone, and substitution while armless.
The shadow clone was for suicide clone explosion while he hid under the earth.
I suppose if his flight is restricted he can rely on those plus use a clay centipede like he did against Itachi.
Mr. 5's durability how good is it? I don't recall it has been forever.