So basically, you are talking out of your ass. You gave up on all of these show ages ago, and have refuse to give the another them another try, even though they have all massively improved in the last few years.
That is complete bullshit. I sure as fuck gave Legends of Tomorrow a try after Season 2, a few days ago I watched the episode of Season 3 where a bland woman they pretended was Helen of Troy had magic powers and Dum Dum Duggan was involved because why use a good villain when you can hire an admittedly good actor to play the same shit villain again and again and again. That was after seeing them somehow get tricked by the bad guy from Titanic in the stupidest way possible, watching the show fuck over DC's Isis in a way almost as offensive as what the movies are doing to Shazam, seeing them rip off Spielberg's second worst movie (ET sucked when he did it, and the current Legends brain dead writers/producers are no Spielberg), and seeing Dum Dum Duggan get ressurected. I got through a bunch of Season 3 fairly recently is what I'm saying (I'm glad Netflix gets all of these shows), in the vain hope that I may see what people like, but much like most shitty comedies its just annoying noise. So, yeah, I know Legends of Tomorrow, and Season 4 is no different, except it has one less good character, meaing Mick is the only real character left on that farce.
I haven;'t watched a single episode of DD Season 3 or Agents of SHIELD post them becoming nazis, but that's because I don't want to see Daredevil's complete fucking of Bullseye and Kingpin, and as for AoS I don't watch shows that turn all their characters into Nazi's, even ones that reenact that infamous season of Dallas (I loathe fake future stories, so even without the Nazi stuff in Season 3 I wouldn't have watched Season 4). But, I know the seasons well enough, you don't have to watch something to be informed about it. Neither show has gotten better, they just got worse.
EDIT: Also, I stopped watching AoS after Season 4, and the first half of season 4 was the last good part of it. I got confused about the season numbers and said I stopped in Season 3, but it was season 4 that killed the show half way through with its Nazi shit.
As for Arrow, anyone who complains that I didn't watch it can fuck right off. Oh, a hero is arrested again? Oliver quits being Green Arrow again? Its just repeating the worst parts of earlier seasons, but worse. Same with black Lightning, a show that completely self destructed in its first season.
I'm really struggling to wrap my around someone actually thinking the first season of Legends of Tomorrow is the best. I enjoyed at the time, but it is the series worst season by a very large margin. We're basically talking about the difference between MCDonalds (Season 1) and a 5-star restaurant (Seasons 2+).
Season 1 of Legends is the only one that isn't a farce. It had a good story (I don't care if Vandal Savage and Hawkman's actors were shit, the story was good), it had real characters that you could care about instead of one dimensional comedy stereotypes, and it had stakes and emotional moments. Outside of the pointless murder of the second best character on the show last season, there hasn't been a single good serious moment since season 1. Also, watching Season 1 shows that Sara and Ray used to be good characters. They used to be skilled heroes, not a pair of incompetent shit heads who don't deserve to lick Rip Hunter's boots, much less go around fixing up time. Its shocking to see how Routh and Saras actress are playing literally different characters in all but name after Season 1.
Also, its ridiculous to call Legends of Tomorrow post season 1 a 5 star anything. Even season one wasn't the best Arrowverse show (even if it was very good), much less the seasons that fucked the JSA or turned the show into a seth Rogen stoner comedy by somehow lazier and less funny.