It has slow transactions and the fees are high, and it is the cryptocurrency frontier.
What do you think will realistically will take Bitcoins nr1 spot in the future? Bitcoin Cash maybe?

It's not better than other coins, it is just the first coin. Bitcoin Cash is also not better than other coins it is just a slight alteration on bitcoin itself, just like litecoin is. Ethereum is the best contender at the moment I think, but there are loads of interesting projects that could become a hit too.