I'm sure if I sat at a computer for the 8 years Obama was president and ran every public statement he made through a fact checker, I could find 300 lies. Easy. Especially if I took opinions of his I disagreed with and called them "lies" or counted the same lie told multiple times separately.
I don't really dispute any of Trump's lies, assuming he was trying to state a fact. The "biggest inaugural crowd ever," "I never did business in Russia," yes, lies. Some of the stuff that gets called a lie by the fact checkers are matters of opinion, like "this is the best economy we've ever had."
My point is that they lie in wait, just looking for Trump's lies, whereas they pursued Obama and other pols they like more with nowhere the same fervor. Obama only got called out by the media at large when he lied about something really big and consequential, like if you like your doctor/plan you can keep it.