Well she is the DCAU's version of Power Girl. In the current New 52 run, Power Girl is just Earth 2's Supergirl.
Eh, every once in awhile someone brings up another show and then there's a dick waving contest about which show is better. For the most part, not really though. The Flash and Agents of S.H.I.E.L.D. OTs are fairly positive. The Arrow one is a bit more cynical, but that's understandable considering how this season has been going.
Basically, the reason why comic threads end up like that is because people who know nothing about comics swoop in and shit talk comic stuff. Then, the people who are actually invested in comics as a hobby (such as myself) get upset because people are shit talking the thing that we invest a great deal of time (and money) into. The part that makes it really bad, though, is that the people talking smack act as if they are some sort of authority on the matter, which they aren't and they never were.
It's not that comics are serious business, it's that because comic book stuff (shows, games, movies, etc) is so popular right now that these comic-related topics bring out everyone. So you've got your typical assholes mixing with people who are genuinely excited and then you get a thread that's exactly like any other thread on a popular topic.
I hope there aren't any. Bryan and Mike said they are done with the Avatarverse in terms of animation. My problem with DB is that it hasn't fucking stopped. Ever. ATLA/TLoK can have their ending and leave it there.