Before we decide on which is more benefiting, Remarketing or shopping campaign let us see and understand how do they work?
The Google shopping campaigns are easily manageable and have benefits like bidding is much simpler, easy to set up new campaigns and it is a great tool to share your workload. Your products are already added to the list in Shopping Campaign format by Google itself. With google shopping campaign, you can browse all your products directly in AdWords, set campaign level priorities (if you have your product in 2 different campaigns) etc.
Remarketing (also known as retargeting) aims at bringing back those visitors that bounced off your site. When the visitor is surfing other sites on the Internet for similar products, you can show them highly personalized advertisements based on the actions performed on your site. There are a whopping 2 million sites and reaches 90% of people on the Internet. You can track the visitor and reconnect with him in different formats. Statistics say that the website visitors who are retargeted with display ads are 70% more likely to convert.
I think it is better to work on Remarketing techniques if you have an E-commerce business.