I have no idea about eCommerce and planning to sell my product online. I am not sure which marketing agency to use and which dropshipping is the best?
Firstly, you have to check if selling through dropshipping or whatever is a good choice.
This all belongs to: MARKETING STRATEGY.
It's not about which company is the best or which platform, if you have this problem it's because you lack of a real plan.
You need to take care of Marketing. Marketing is the lifeblood of your business, outsourcing it without even know what's good or wrong, it's like givin the key of your house to the first encounter of the street.
An entrepeneur is basically someone who's expert about marketing and knows numbers.
What is your product? What is your angle of attack which makes it unique?
How much is your budget?
You have to deep define your market and don't fall in the shiny object syndrome: to try everything that seems new or suitable to your business and mistake a tool as a strategy, or looking for the holy grail