Babar isn't tough enough - you won't ever believe that Imran would allow his fellow team mate to carry him like Madhuri Dixit in front of whole stadium - even for a broken leg or a cracked skull. Chances are high that, Babar's batting will suffer to lead a struggling side (don't be fooled with CT win - that mid summer's night dream is over in 4 match). He has a far more critical role to perform - be the batting leader of what is easily the worst batting line-up among serious cricket nations & maintain 50+ international average in combined 3 formats.
Imad should never, never, never be made PAK Captain - it's like Larry Gomez leading a team of Richards, Lloyd, Lara, Marshall, Holding, Garner, Roberts & AmbroseHe is just not good enough for a fixed spot in ODI side. May be T20 is his limit.
Whole PAK might not like it, but only, only, only realistic option is Amir - someone who can lead from the front of a young team. If he is clean enough to wear PAK Cap, he is clean enough to strap the arm band.
By the time Hasan might be ready, I believe it's better to invest on Shadab, rather than him.
How is Amir a good option?
The guy has literally 0 captaincy experience
Typically jazbati Pakistani thinking