I myself repeatedly asked myself this question, and earlier it seemed to me that ETH has much more prospects than Bitcoin, but time has shown that I was wrong. Bitcoin continues to dominate and now many large investors buy it. Perhaps this is due to the fact that in fact, apart from Bitcoin and etherium, there are no normally working platforms. If in the near future something is not thought out much better and more promising than Bitcoin, then Bitcoin will remain the dominant cryptocurrency for the next 5 years.