Misbah has to go.
Azhar is just beginning to blossom as an Opener or at Number 3. He is tactically unproven and it may affect his batting it he becomes a Captain.
Sarfaraz will be overloaded if made into a Captain and it will be too much to play 3 formats and Captain 2 formats.
Shafiq is not Captain Material.
Wahab is not Captain Material.
Amir may be but not the sort of guy who can impose himself on the team or opposition
Best Choice is YK as a stop gap Captain.
If not, Butt is our next best choice as Captain, maybe bat down the order.
We really don't have many choices
Captaincy wise, he is not a bad choice; but we have to look his stats outside AUS.
Till his mid 20s, excluding AUS/NZ - Salman averages around 23 in about 25 innings. If I take out PAK, it comes to below 20 level. That's actually lowest by any PAK specialist batsman with 20+ innings. In fact among WK's probably only Wasim Bari averages lower than him in that filter (Or Moin as well).
If I put a filter of openers with 20+ innings, it's average of 22, which is comfortably lowest - even by same filter MoHa averages 38 & Farhat over 30.
These are shockingly poor numbers for a specialist opener, who was given a run of 30+ Tests & played for a far better batting unit having some of the best middle orders behind him. Butt's career is a mystery, which is inflated by his scores in toughest of opponents AUS (even at Lord's he scored 93 against them !!!!!), but apart from that, he is just a bit better than Saqline, Kumble or Warne. We can give some weightage for being opener, still these are shocking numbers for appointing a Captain, out of game for 6 years & now probably in his mid 30s.
As you said, not best, the only option is YK. PAK's next 15 month's Test schedule is WI, BD, SRL & IND (?) - I can safely say that, in those 12/13 Tests, he'll score at least 1K runs at 50+ average, with couple of hundreds, if not more. Movement is his biggest challenge at this age, but still he is the best player of spin & once set, he can score big. Afart from 2 innings of Azhar, in last 3/4 years, I think every PAK innings of 150+ are scored by him - 175*, 218, 177*, 203, 176, 201*. Once set, almost unmovable object on his suitable condition - which is where PAK is going to play next 10+ Tests. Therefore, for sure, he is not going to struggle to justify his spot in playing XI.
Apart from that, he is well respected; far, far better tactician than Misbah & he actually can operate with 3 pacers or can attack with his spinners to hunt wicket. He won his first Test as Captain against IND without Inzi, won his WC T20 tournament as well. I am sure, he won't have allowed this WI or Methews's SRL to win a Test against this PAK side; neither ENG or BD would have got away with a draw in UAE. His only issue can be man management, but this time he will have full support from his team, unlike last time & from his Board/Coach as well.
For 1.5 years, YK is actually the only option; while PCB can appoint Amir or Babar as his deputy. Putting Azhar or Sarfu as Captain is a backward step & making them Deputy under YK is a blunder.