>>10504873They have decent articulation I would say. They have all the requisite joints for super articulation, but they don't always engineer them in the smartest ways. Their biggest advantage is that most of them are relatively easy to modify in a non-ugly way. Example, for an amateur to mod a Marvel Legends for greater articulation, it's probably going to be ugly and very visible. McFarlane tends to build his figures in "layers," so you can often hide cuts or shaved-off parts underneath something else. A good example of this is a balljointed torso which overhangs the stomach by a lot. You can pop this apart, cut into the socket to create greater range, and when you pop it back together, the torso piece hides all of that. McFarlane also uses a fair bit of soft plastic, which is relatively friendly to flexing out of the way and/or being cut into easily. For $20-25 figures in this day and age, I think you should be relatively pleased with what you get.
tl;dr: they're not always great out of the box, but if you're willing to do a small amount of legwork, they're pretty easy for even amateurs to improve on. I would recommend you get one of the MK11 Spawns, Commando Spawn, or Throne Spawn. All of these are pretty good figures and should work for a basic Spawn. There are also some really nice wired cape + chain sets you can buy if you want that classic flowing cape Spawn look. I dunno about Black Manta though, don't own any of him.