Any of our comic buffs have an opinion on this one? Been gradually building a digital comics library out of these Groupees and Humble comic bundles, but I know nothing about any of these that I didn't learn from watching the first couple episodes of that live action Witchblade TV series from when I was a kid.
Top Cow comics are almost nothing but irredeemable trash. To me, they embody the worst trends of 90's comics, the grimdark edginess combined with horrible proportions and cringe-inducing, sexist art. They have refused to move on from that time, dwelling in the absolute nadir of comics storytelling. Even DC, for all of their problems, are leagues ahead of Top Cow in terms of both artists and, to a lesser degree, writers on staff. As for the individual series on offer here:
The Darkness varies in its readability, from "pretty good" to "why am I even reading this?", and Witchblade is garbage from beginning to end. The Darkness video game is unfathomably better than the comic series on which it was (veeeeeeeeeeeery loosely) based.
I have not read these particular ones (the IX issues), but people seem to like Stjepan Sejic's stuff. I can't stand it. His art looks like a DeviantArt Phil Noto ripoff and his writing is extremely subpar. You may have seen his dumb comics about Superman's alien penis or whatever on the internet. Gives me Kevin Smith flashbacks. You know, the guy who decided it would be a good idea to retcon part of Year One so Batman pisses his pants.
Down is from Warren Ellis, but it's far from his best work -- probably near the bottom, to be honest. It's still not bad, but the fact that it's in the BTA tier tells you a lot about the rest of this bundle. The J Michael Straczynski books... He has his fans. I don't think he's bad either (mostly -- Superman: Grounded was truly horrible, in ways you likely thought impossible), his Thor run was pretty okay, but mostly he's not my cup of tea.
The rest I have either never

ing heard of or simply haven't read.
(by the way, the fact that you watched a Witchblade show, from the early 2000s, when you were a kid, makes me feel super old)