What sites do you check?
What are your criteria?
Do you have some system?
I believe you have incentive to share this information because more of us invest in one coin, more the price is.
First, I check the price on some exchanges such as bittrex, Poloniex, shape-shift, etc.
Find out what the idea/read the white paper, what something new and better offered to user since bitcoin is the best cryptocurrency so far and still develop according to the market.
And then, from the charts price in the last 1-2 years and conclude the idea which lead to the future usability and demand of the coins, that's how I choose one.