The answer is always going to be yes. Amazon is the biggest, so it will almost always be your most successful marketplace due to its size and popularity. I almost always recommend starting there if you’re new to marketplaces. Once you’ve established yourself on Amazon, I then recommend moving to eBay, Walmart and Jet.
Depending on a bunch of other factors (price competitiveness, free shipping, delivery time, etc.), sales increases vary on a case by case basis, but there is an increase of sales, and that at the end of the day is your goal. As soon as you have conquered these 3 marketplaces, we recommend looking at next 4 marketplaces, Newegg, Sears, Rakuten, Overstock. At the end of the day, it is getting your product listed in as many marketplaces as possible as long as it increases the number of sales, and increases the profitability of your business.