"The greatest suspension of disbelief you'll have to get over isn't the transporters, it's humanity being among the most noble sapient species in the galaxy.
If you can swallow that wildly fantastical pill, it's amazing."
-my standard pitch, then when they get to the mirror verse I tell them our timeline is about to get a cameo.
Same! (Unless it's someone who likes a to roast their media a little, then I start them off with TOS "Savage Curtain" -- the Abe Lincoln episode. Whatever sets the hook!)