Merch by Amazon OR Own On-Demand Print Solution?

I need one suggestion from here. Actually this is frustrating me from last 1 month. I want to start a side business of On-Demand print.

I have two option available one is “Merch by Amazon” and second is “Own Mobile Applications and Website”.

As my aim to get the maximum profit from my selling. As I have seen that many people start this business already but through Merch by Amazon. But this is my long term goal.

So I am confused that rather than go for Merch by Amazon shall I go for own solution. Because at the end this creates brands. 

I need your thoughts, please!!