From an investment POV you need to weigh the potential reward against the risk you are willing to take. Sure you can invest in top 10 coins and you will probably get a decent ROI after a while since the crypto market is still young. But I like to look for the projects that have a lot of promise that aren't on everyone's radar. Projects that might not have done well with their ico or didn't do an ico at all. If you can find such projects with an active dev team that means those devs are working their butts off to make their project successful. For me those projects are XTRABYTES (XBY), SPECTRECOIN (XSPEC) and Internext (INXT).
XTRABYTES is developping a secure, superfast codeagnostic platform, Spectrecoin is a highly secure, anonymous coin and Internext is working on a decentralised internet. Those coins/tokens are not just copies of other existing coins with some added bells and whistles, the are original projects that have a real change of finding large adoption. They are also coins that are highly undervalued at the moment and can give you a very nice ROI.