Things have value because they have demand. Things have demand because they provide utility. Relative utility determines relative value. And actual price is the ratio of demand:supply. So ask yourself, do any of these altcoins provide some utility bitcoin doesn't? To the extent any do, they will have value to the extent of their marginal utility over bitoin and other altcoins.
Every altcoin is trying to provide some marginal technical improvement over Bitcoin, and hence some marginal value. But Bitcoin's first mover advantage, resulting network effects, and stable/reliable core dev team and non-profit foundation all provide significantly more utility - namely trust - than the marginal technical improvements of most altcoins, hence why most will never approach Bitcoin in value.
Litecoin is one exception, as the first widely trusted altcoin with a few technical improvements over Bitcoin. Ethereum could also be a possible exception to this, if they can make it work. Very ambitious, will probably have growing pains for a few years at least.
Every altcoin is trying to provide some marginal technical improvement over Bitcoin, and hence some marginal value. But Bitcoin's first mover advantage, resulting network effects, and stable/reliable core dev team and non-profit foundation all provide significantly more utility - namely trust - than the marginal technical improvements of most altcoins, hence why most will never approach Bitcoin in value.
Litecoin is one exception, as the first widely trusted altcoin with a few technical improvements over Bitcoin. Ethereum could also be a possible exception to this, if they can make it work. Very ambitious, will probably have growing pains for a few years at least.