Best altcoins? I think it's Neo or Etherum. That's the 2 altcoins I feel most potent. I spent a lot of time to learn about these 2 altcoins.
You can see that Neo is a well known currency and only behind Etherum and Bitcoin.
It is known that there will be many supply and demand. So we can conclude that these two altcoins will increase in price in the future. If you do not have much money then I think you should buy Neo, it is a good altcoin and have cheap imitation.