I am with you @Denise - I prefer Aligned Left to poorly done Justified any day.
I checked and the New York Times, the Wall Street Journal, and the Washington Post all appear in Left Justified. I suspect there is a reason.
Interestingly, my Kindle app on my iPadS is in Justified, and when I check for 'rivers' I really don't find or notice one - that might be different if I would choose a different font, maybe. I don't mind the Justified on my Kindle app because of the lack of rivers - the text spacing is not objectionable, but the page width is much wider on my Kindle than the newspaper columns on my Mac in Safari, or on my iPad in Safari.
I do prefer Aligned Left, although if Justified is well done, I don't find it too objectionable. But often it is done very poorly as in the sample at the top of this page