I mean Bitcoin is number 1 because of there popularity since it started operation many people in the country engaged about it business, investors put there capital money due to a good leadership teamworks of the team jobs, likely crypto can easily change fastest and higher value of the market from now on a days.
Bitcoin is already number one in most every aspect. besides that bitcoin has such a big community now and is growing day by day so i really think that it is one of the main factors. But currently the main problem with bitcoin is that the transaction takes a lot of money and still takes hours to confirm. While other coins have a much faster speed with less cost, because each coin has its own philosophy.