The altcoins and the so-called "shitcoins" outperformed btc in the rallies of the spring and fall of 2013. They outperformed in earlier rallies, but the market data I find is kinda fuzzy. They are outperforming now also. Some of the many altcoins will turn into major winners like ETH, XMR and Dash. Most will plummet in value in the next crypto bear market. You don't want to be long something like dogecoin when the rug is pulled. If you hold a nominal amount in the promising coins, however, you could have some massive Massive winners. Monero was pennies a year ago and is now $30. I first bought ETH under $2. It is now $90. Wish I wouldn't have dumped after the DAO hack. Only a handful of cryptocurrencies and digital assets have outperformed BTC over a two year or even one year time span. GameCredits is one. I am not advocating it. The others are probably XMR, Dash and XEM. There might be some others. You could go to the Poloniex charts section and create a list as the charts are priced in BTC. Good luck.
There was a Chinese Ponzi that used Litecoin, that was pure double genius. First he bought up LTC, then when running the Ponzi, the payment was required in LTC, what also pushed the price up even higher. At the end he transferred the LTC into BTC and cashed out without crashing the price. This should be in text books, it was so beautiful... https://blog.bitmex.com/chinese-promoter-pumping-litecoin-via-ponzi-scheme/
Quote - "Litecoin was announced in 2011 with the goal of being the 'silver' to bitcoin's 'gold'. At the time of writing, Litecoin has the highest market cap of any mined cryptocurrency, after bitcoin. Here's our guide to show you the crucial difference between bitcoin and litecoin.itecoin was announced in 2011 with the goal of being the 'silver' to bitcoin's 'gold'. At the time of writing, Litecoin has the highest market cap of any mined cryptocurrency, after bitcoin. Here's our guide to show you the crucial difference between bitcoin and litecoin." http://www.coindesk.com/information/comparing-litecoin-bitcoin/
"Litecoin Explodes Higher After Flood Of Chinese, Korean Buying In Search Of Latest Cryptobubble" http://www.zerohedge.com/news/2017-06-17/litecoin-explodes-higher-after-flood-chinese-korean-buying .
Litecoin is up 1000% since March, from $5 to topping at $54 yesterday, currently at $50. Poor Bitcoin only tripled in the same timeframe. Bitcoin's technical changes coming in August capital seems to be flowing into other cryptos, "just in case" not everything is going smooth...