I was having this debate with someone who was saying its the difference between gold and silver. One is not necessarily better then the other. I however, take the stance that Alt coins are really just riding off the success of bitcoin and in the end of the day, really serve no useful purpose. Can anyone name one feature that an alt coin can do that bitcoin cant? I don't really see minor differences in how many total coins exist, or the different mining strategies that are employed as features. Features are, send money electronically, etc ,etc.
PPCoin augments "proof of work" with "proof of stake" to secure the network which is much more efficient. So, all things being equal, transaction fees with PPCoin should be lower than Bitcoin. And I believe transaction confirmation times are half that as Bitcoin?
Freicoin has a 5%/year demurrage rate that goes to miners forever. So, this may encourage a more secure network, and lower transaction fees. The demurrage could also help increase monetary velocity.
I believe the only thing different with Litecoin is the hashing algorithm and faster confirmation times?