Coinwatch for ios or android is perfect for this.
CoinWatch has a bug that if you set up an exchange for tracking( for an example, you pick bitfinex as your source for altcoin prices), sometimes after reloading the app you find out that your settings has been resettled and you need to update it again, other then that the app is okay, but I couldn't find any feature that is not available at the blockfolio app.
I would stick with blockfolio as they have the most advanced version and I believe it flawless from bugs.