I'm not going to tell you which altcoin to invest in, I think the financial responsibility is on each of us individually - but I can advise you not to invest all your money in one coin, reduce your risk and invest in more of them that you think will end this year with at least 100% growth.
Of course, there are various speculations that BTC will be worth at least $100 000 by the end of the year, and some are speculating about as much as $300 000. I suggest you visit CMC, look at the top 20 or even 50 coins and their history in at least the last 6 months, it can give you some guidance in what to invest your money in.
This is particularly true and I totally agree with you. Investing in bitcoin is less risky and it is the most probable investment you should invest it. However, you'd have to buy and hodl for a very long time because it's an investment for the long term.
If you're thinking of an investment to give profit in a short-term, then your best option is to invest in altcoins with potentials. There are a lot of altcoins that are actually shitcoins and you'd lose your money if you invest in them. So take time out to study coins with potential that you'd make profits with. You should check out coinmarketcap.com