In current times, Shaheen Afridi is one of their best, They also had Naseem Shah but unfortunately for them, he got injured before the World Cup. Shadab Khan on his day can be devastating.
I rate Naseem Shah higher than Shaheen Afridi as a bowler. Naseem Shah can bowl anywhere in the match, while Shaheen is usually good in the first spell. Shadab Khan is not in his best form and has not performed consistently with bat or bowl for the past few months. He is leaking runs in the middle overs with an economy rate on the higher side. Spin bowling is a major concern for Pakistan going into the World Cup. If he does not perform in the World Cup, then I am seeing Shadab out of Pakistan's playing XI after the World Cup.
In the past, Pakistan always had better bowlers in the form of Wasim, Waqar, Sohaib Akthar, Muhammad Amir, Muhammad Asif and a lot more. They were known for their fast bowling just like India is always known for their strong batting.
After Naseem's injury, Pakistan's bowling is not looking very lethal in this World Cup. Shaheen and Haris are good, but you can not win a match with just two quality bowlers. Pakistan's bowling in the middle over is very poor and they leak runs in those overs. As far as Indian batting is concerned, they have been exceptional from the beginning, and their top order is always dependable. In the middle, they have explosive batsmen who can turn the game in two overs.