Short list of my top 3 coins that will see the biggest gains by 2020:
1. Matrix AI Network
2. NEO
3. EOS
Biggest gains by 2020? You will be lucky if these coins are still around by 2020. If I were you, I'd get your money out of EOS and fast. A lot of newbies fell for the EOS hype, that's why
almost everyone that holds EOS are people that joined crypto in 2017. There are almost 0 tenured crypto users that bought any EOS, because it is an obvious cash grab/scam. dPOS doesn't work, and EOS has already had a slew of problems. Even the huge day one issue when they had to pause the blockchain. EOS is not a cryptocurrency, as it doesn't have the three foundational pillars of crypto. Which are:
Immutability
Censorship resistance
decentralization
EOS has none of these, as the blockchain has already been rolled back, the BPs have the ability to freeze wallets, and there are only 21 BPs so no decentralization. Also, why did the EOS team need $4 Billion dollars for the ICO? Last time I checked Bitcoin required $0 to be developed and launched. Obvious cash grab.
EOS has far too many flaws for it to be a functional cryptocurrency. It has been slowly bleeding out and it will continue to do so. The only coins truly worth holding are the ones that have withstood the test of time and the ones that hold merit.
The three picks should be Ethereum, Litecoin, and Monero.
Ethereum is worth holding because it has the largest amount of developers working on the platform, and Sharding is cutting edge blockchain technology for true on chain scaling. Once this goes live, Ethereum will do great. Very large hashrate, insanely high tx/day count (good network activity) and it has always been the #2 coin (for the most part), and I don't see this changing anytime soon.
Litecoin is worth holding because it is the second cryptocurrency ever made. It is digital silver (much like how Bitcoin is digital gold) and Litecoin can double as a testbed for Bitcoin upgrades, as the code is identical for both coins. Segwit went live on Litecoin nearly a year before it did on Bitcoin.
Monero is worthing holding because it is one of the oldest privacy coins, and one of the only privacy coins that actually work. Most other privacy coins have flaws in the way the coins are anonymized, and with a great amount of scrutiny, the coins could be traced.