A friend of mine recently switched back to the CTA from the Metra after a recent move made it more convenient to commute via the CTA. And she likes the CTA much better!
She rode the Metra for about three years, dating back to when the CTA three-tracking project added 10-15 minutes to commutes on the Red, Brown and Purple Lines. During her Metra days, she told me she liked the "general" punctuality of the schedule, and the speedy commute with way fewer stops than the CTA's Red Line.
But now that's she's back on the Red, she explained a few reasons why she's liking the CTA more than the Metra:
"While riding Metra, I missed the urban authenticity of the L. Everyone rides the CTA -- professionals, students of all ages, blue collar workers, Cubs fans, everybody. I choose to live in an urban area and I like to be immersed in its diversity.
"A pleasant surprise upon returning to L commuting is how efficient the trains are after the huge three-track project and all the work to fix the slow zones on the Red Line. And the train monitors at Belmont (the screens that say when the next train is coming) are awesome!!"