Which 10 Altcoins are the oldest?
Currently I can think of Litecoin (2011), Namecoin(2011), Peercoin (2012), Ripple (2013), GridCoin (2013) and Dogecoin (2013).All of them are active till now.
Some more can be found here https://en.wikipedia.org/wiki/List_of_cryptocurrencies
It is quite surprising that the age doesn't matter a lot. Litecoin, doge and maybe ripple still mean something, whereas the 3 others don't. And ethereum was released later and yet it doesn't make the coin worse. I think that age matters in certain aspects. For instance, a brand new coin has to exist for about a year to prove that it is okay. But I don't think that it is important whether a coin is 2 or 4 years old.