Hi Oviyan. Check out the Designer Reports on the Iconfinder blog - https://blog.iconfinder.com/designer-reports/home. There is a ton of useful information including info on which styles are most popular. I don't believe hand-drawn icons are in high demand but that's not necessarily a reason to avoid them. There might be a good long-tail opportunity there.
If you look at the "Style + Category" pairing with unmet demand, you can see that hand-drawn social media icons have a low supply-to-demand ratio. The supply-to-demand ratio is a relative indicator as to how many icons there are to meet search volume. A ratio of 1.0 means the supply of icons is about even to the volume of searches for a particular keyword, category, etc. A ratio higher than 1.0 indicates there is too much supply. A ratio below 1.0 (in this case 0.78) indicates there is still room for more supply as the demand is higher than current supply.
What is more interesting to me, though, about this chart is that if you want to try out a new style, "Smooth" icons seem to be in demand but with less supply. There is a clear opportunity there.