Both platforms are valuable, but each has unique advantages. Substack is more predictable for established writers. Writers with a specific expertise or niche can effectively build an audience on Substack. A following matters less on Medium in the age of the Boost program. Getting Boosted is the key to success in today's Medium, which can be frustrating, as it can lead to feast-or-famine results. Still, you don't need to stick to a niche to do well on Medium.