Invest on altcoin is always risky man, it's hard to have a good one with huge growing. The best option to choose is coin from top10.
The problem with investing only in top ten coins is that you wont make any fortune amount of money if you invest in them now, if you are really looking to make a good amount of money you need to always find good projects with good returns and you could find some good projects all the time, the risks are higher without a doubt but the perks are higher too, you just need to spend time to learn about their project before investing in them, it is not an easy job, you need to scout over twenty to hundred projects to find one.