I mostly prefer doing CPA affiliate marketing than CPS affiliate marketing offers, even if CPS is more rewarding. In CPA, you don't need to complete any purchase of items, either digital or physical item. You just need to complete a certain action to count as a lead. The only demerit I found on CPA offers is that, the offers you're marketing centres in a particular geographical area, meaning, you can't advertise or market it to another country users, like Nigeria when it is specifically for Indians. That's the downside about it, finding users from a given country is quite hard to find especially when you aren't residing there, or no anything about the country.