Some of the altcoins such as Ethereum, Monero have actually proven that they are quite undervalued and have a lot of potential. So it would be false to say that altcoins have no reason for existing.
According to me, other than Bitcoin, Monero is the most preferable market coin. With a market capital of 3 billion dollars, it has the potential to cross the mark of $300 per annum within two to three months. Also, being completely anonymous makes it a good altcoin in the market.