I personally think that this is a loaded question but it's interesting and relevant, it's my opinion that there are many cyrpto currencies out in the market. But many of them are not good and are irrelevant.
I think some of those who can make a huge breakthrough are as follows:-
1. Ethereum- well must be pretty obvious,but I think that it should be mentioned after all. This is the coin which the most potential currently.
2. Dashcoin- this one is well planned and made a big jump recently and can be trusted so far.
3.Dogecoin- OK,I admit that it may be received as a joke and criticized by many but it is making a rapid progress.
But this is unstable, and in its defence,so was Bitcoin.