The honest answer is that there is no single way to tell.

My personal process involves finding a market space where I think crypto-based companies can outcompete regular companies e.g. social media.

Then I attempt to find as many of the competitors as possible in this space and compare them to see which one I believe will be the best in the long run.

I like to look at tonnes of different factors e.g. opening price, the tech, the team, the platform etc. in order to determine this.

I try to write up as many ICOs in this manner as I can. Have a look at the upcoming Aventus and Red Pulse ICOs if you're looking to invest in any :)