Learning is one of the best investment which is an asset. Both the learnings have it's own pros and cons. First let's see the free online courses, it's always good to start from the free courses to see whether the subject actually creates interest. If you able to see the course is useful and the content is fulfilling all your doubts in the subject then you can learn from the free online course. If not search the paid online courses with rich content which matches your requirements. Usually the free courses dont award certificates for your learnings, certificates are essential to back your learnings in the job market.In paid courses you have to invest money, if you are not able to dedicate your attention and time in the learning process then dont go with paid course. Paid courses are usually comes with subscriptions, which cost high. Hence start with free course and understand your learning outcomes and if it is benefitting your future growth go with paid course and get your certification. In short choose the training method based on your interest towards doing the course, and future goals. Keep learning!