Although it's true that market cap plays an important role when deciding on which coin to invest, I'd be careful in taking it as a definite measure... As you say, the case of Ripple is an example where market cap deceives, people saw it on top of the list and threw their money on it without researching what it was about and without noting that other coins with still lesser supply could grow much bigger given the needed time. But believing that market cap is a trustworthy measuring stick is also tricky, I recommend the following reading in order to take market cap analysis with a pinch of salt:

https://hackernoon.com/why-market-capitalization-isnt-a-good-metric-for-cryptocurrencies-36a134e074f7