According to me the 5 best Altcoins to consider because of their wonderful performances are:
1.   Ethereum : provides the best way to make smart contracts. Created a wonderful use of cryptocurrencies for binding people across the world into agreements which are enforceable on them by the power of technology.
2.   Neo: Neo is the chinese Ethereum a contender created by Chinese giants to fight against the mighty ethereum. Both serve the same purpose and I wont be very much shocked if it takes over the Ether in coming years.
3.   Ripple : Ripple the banking coin creates an easy world for settlements across the globe. The reason it can be used as a currency far better than bitcoin is because of the low transaction fees it has. But the only drawback it suffers is the centralized restricted supply.
4.   Litecoin : A step towards a better bitcoin. Litecoin has a blazing fast speed and creates new blocks much faster than that created in bitcoin. This means faster settlement rates at similar transaction fees.

Just make sure to do your own research about any coin before investing in it.