For most people who are interested in cryptocurrencies, Coinmarketcap (CMC) is the default website for comparing cryptocurrency prices. You can call it the google of cryptocurrency. CMC power is so strong that coin developers list their coin on CMC before adding it to an exchange.
Coinmarketcap is indeed a great site, with an easy and intuitive interface. However there are more than a few good coin-tracking-sites out there, that pose an alternative. Some of them use Coinmarketcap API and others pull in their own data.