Most "coins" all do the same thing or run on the same blockchain, so the only thing that provides value to the others is how well known they are and the news around them such as support, people interested in buying them etc etc. But all the blockchains are similar they all do the same thing besides perhaps size of the transactions that can fit in each block.

That being said other coins like Ethereum offer a unique blockchain with more features and another important keep a central development team that can alter and adapt the coin to markets and changes in the future which is very powerful.