Most frequent question in eCommerce field because both are competitor of each other. Read the below explanation then reply to this topic if you have any question regarding this.
Magento and Shopify both are powerful and spectacular eCommerce platform to go ahead.
In case of Magento, Large eCommerce companies like Charlotte Tilbury and Saraiva utilizing that service.
Magento infrastructure is powerful and made for only large companies, I personally utilize Magento 1.5 years and their internally features are complicated and a beginner can not understand their structure. But it was awesome experience. I had taken 2 month to completely understand Magento deeply. If you are familiar with attributes then you may go ahead with Magento. Otherwise first read articles and watch tutorials to understand their fundamentals then start your journey with it.
In case of Shopify, new and emerging user friendly interface but premium. In my opinion, you should go with shopify because with Shopify you do not need to purchase any web hosting plan because shopify host data itself with unlimited products and bandwidth. Shopify basic package starts from $9 which is most reasonable and excellent from my perspective.
Shopify will give you free eye catchy templates, which helps you to build your own online store. You can upgrade your Shopify plan anytime when you feel satisfaction. Shopify also give 10%-20% discount on annual plans.
If you can manipulate or handle complexities then go with Magento unlike for user friendly and trendy interface with in reasonable prices go with Shopify.