I generally don't dislike any characters on anything but as of late I found Maggie slightly irritating. Note slightly.
Mainly, Maggie hardly associates with the main team of Supergirl, and tends to always form their own camp with Alex on issues, and Alex often being the irrational and impulsive one in most matters. That causes minor schisms within Kara's team and more often than not creates an Alex vs Kara scenario.
Like last episode when they withheld Cadmus whereabouts from everyone and just did stuff on their own.