If you are looking for big returns short term, the only option I can think of right now is going with a top ICO
Quarkchain stands out to me, aiming for some seriously high TPS speeds and they've got a team with experience to pull it off.
https://quarkchain.io/Can't call me a shill with this as it's an ICO, Telegram is massive, hype is huge, it's going to sell out very fast so I don't need to promote it, I can see 10x from this in a short period and if they pull off even 20% of their goal for speed, it'll be the fastest coin.
Also offers smart contracts via Eths virtual machine, you could instantly port your Eth dApps over to Quarkchain and get higher performance and better scalability.
No one has a glass ball on these sites but this one has tons of potential to go up, Holo went up over 10x from ICO and this will blow it out of the water if they get even a small % of their TPS rate, it also benefits from plug and play with Ethereum apps.
I'm buying in myself, probably put 0.5 BTC on it or maybe a whole, the team is solid so I've got faith on something which really seems too good to be true.
They are aiming for 100,000+, even 20,000 would be over 2x as quick as the current fastest coin, Visa being a centralised system operates at 24,000, Quarkchain will be fully decentralised and faster.
Nano being one of my favourite coins due to it's speeds pomotes a max of 7,000 TPS
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If I had to recommend a current coin, I'm bullish on Neblio, currently the price is probably a bit high to buy in though, 0.0013 would be a good point if we see a correction.