I dunno, none of the other shows have been on air as long as Arrow. The Flash has definitely seen a dip between the first 2 seasons and Supergirl ratings were a bleeding wound hence the move from CBS to CW. Legends has had a wobbly start all things concerned. Wouldn't surprise me at all if they're all Arrow levels in quality and ratings by the time they reach the fifth season.
Still DC shows suffer from considerable issues, for one excluding Gotham none of them seem to able to survive on a network not named CW. First it was Constantine and then it was Supergirl, wouldn't surprise me if Preacher and Gotham start facing trouble a year from now. Frankly I'm seeing Preacher go the way of Constantine, I hope it doesn't but I'm not getting good vibes.
Once you're on CW then pandering to teenage girls, Olcity and the ever present "CW" problems are to be expected.
Finally DC shows unlike Marvel do feature heavy hitters, Gotham, Supergirl and Flash have more inherent star power than the likes of Agent Carter, Jessica Jones or S.H.I.E.L.D. Daredevil is Marvel's biggest but even he cant compete with Arrow in star power because Arrow made it's name by being a Batman lite show. Supergirl too is Superman lite, same goes for the upcoming Luke Cage and Iron Fist shows, Arrow will always have the Batman/Nolan factor giving it the edge over them. Marvel simply put has done a better job putting no names on the map. DC has 2 wannabe Batman shows, a not Superman show, a not Superman show just a few years back and the Flash. So yeah DC tv has done a dismal job giving us actual Green Arrow and Gotham shows.
So I think both the movies and tv side of DC are equally bad, I enjoy some stuff but I'll readily take Netflix shows over DC shows any day.