Is 72-74 Crimson the 'real' King Crimson? I like the first era and all, The Power To Believe is my favorite, but the Bruford/Wetton era is just killer all the time. They are the only Crimson band where I have many live releases. What a powerhouse they were.
For a lot of fogies, the answer is "Yes". Even though the debut In the Court of the Crimson King was amazing, the band seemed to change with pretty much every album until the Bruford/Wetton lineup. At that point, they'd reached a level of stability in the lineup and an incredible tightness musically, which is important because King Crimson always featured a lot of improvisation. So this lineup was awesome, their "final form", and then they broke up.
When we saw Discipline in the record stores years later, it was a shock. What, they're back? It helps to remember the times; bands did not break up and then get back together years later, or take several-year hiatuses. They broke up and stayed broken up, and fans mourned. The 80's band was originally going to be named Discipline because... well, just listen to the album. But Fripp said that this band had a quality to it that made them worthy of being called King Crimson. I don't know how much the fact that Bill Bruford was also in the band affected that decision, but it probably didn't hurt.
But the Discipline band had a very different sound. Despite two of the four members being the same, they're a different band in everything but name. Then the THRAK band was different again, though obviously a descendant of the 80's band. I've kinda lost track of what they're doing now, but I saw a relatively recent video with three drummers and it was also amazing, but again a different "band" if by that you mean a different sound, different approach, different attitude.
So they're all different, yet all King Crimson, but if you had to pick one version of the band that's the "real" one, it's the 70's band for me. But I suspect that people who grew up with the 80's band consider that lineup the real band, and folks that grew up with the 90's band think that's the real band. (They'd be wrong, though. Kids these days.)