CPA.
There are multiple reasons for this. The first one is that since you are living in Bangladesh you are on the restricted country list in Clickbank, that means whenever you try to create an account via your Home IP you will get rejected. So you would have to find a way to withdraw the money and hide your IP so that you are shown as logged in from a different location outside of Bangladesh.
The second reason is that CPA is easier to promote than Clickbank. Often times, in Clickbank, you have a lot of offers that are PPS, meaning you only get a comission once you make a sale through your website/promotion. And that takes time, sometimes even a lot of money because you will have to go through a lot of testing in order to find the winners. In CPA you can choose between a lot of verticals such as SOI/DOI, which you should begin with, in my opinion. They are way easier to convert but you will get less comission as if you were promoting a product on Clickbank. So you can decide:
-> Clickbank : You need a VPN, and a way to withdraw your money - Lots of testing involved
-> CPA : No need for VPN, no need of external banks - Less testing but also less comission