I think the best altcoin this year is Ethereum, you can see in the Ethereum market has a big community and Ethereum demand is growing from time to time so I think ETH is reliable, so I suggest to choose ETH for your investment.

Litecoin, ETH. 

One of the best for today is the ETH coin! Once the market goes up it will show a good gain!

For me it is still worthy to invest with eth and some  other alts like waves, neo, etn, xspec and the new ins. Eth was proven to be a good long term investment. Waves and neo  they have good projects thus they are stable. Etn xspec are for long term investment also. And ins is still very new and its still undervalued, it will surely give you a good return of investment once it start to kick off.I would advise you to take a closer look at ico and new tokens.
quarkchain, egretia, eloncity,arcblock,sentinel protocol and other 

Check Blockshipping.
ICO ongoing.

The blockchain based GSCP platform is the world's first freight container registry and the first global platform allowing all players in the shipping industry to perform a wide range of transactions related to the handling of containers.
The GSCP ICO offers a set of token features including a Revenue Sharing Model as well as a Market Maker Fund that allows ICO contributors to sell their coins back to the platform at a floor price until Blockshipping has met certain fixed milestones.

I took them already for bounty campaign because I want to take as more as possible their tokens. Via bounty and token sale.


Acorn collective. Soon on exchanges. HITBTC and Bancor. Fund managers invested there.

Enkronos. ICO as well.

GoNetwork

Project Shivom. Zebi, Matrix and CVC are already on exchanges.

Powerledger, We Power, CarVertical and Thrive.

I vote for Ethereum and actively invest in it. He is very promising and can compete on an equal footing with bitcoin. This is a profitable currency for long-term investment

I think there are a lot of altcoins in this market that can make a lot of money. But I'd rather invest in a Refereum.

What about etherum? For me its price went totally down and getting some part of it would be a great investment for short and even long time holding?

It seems to me that we should not take too much risk, so our investment should only be in the most reliable coin. Pay attention to ETH, ETC, LTC. It seems to me that these moments have great potential.

Almost all of the coins have low prices now, but I recommend that, maybe you should consider about some top coins like btc, eth, ltc, neo and iota.