Hey there Old Dog I firmly believe the ABB have a foot in each. They have great originals and also played the hell out of covers and made some their very own. Just my thoughts.

To me - Zeppelin is the mix. The ABB is definitely in Group B.

Duane didn't write.
Gregg is credited for stuff that are 8 minutes long with 8 lines of lyrics. By 1972 - his writing is done by himself.

The band is known for long improv jams.

When Gregg showed Dreams to the band, the verses were not separated by a guitar solo that got longer and longer then became two guitar solos that separated the verses by a mile. Whipping Post was almost a slow ballad. Berry wrote a bass intro and new bass line, Butch changed the time. Midnight Rider was changed. Laid Back has the arrangement closer to how it was written. They seem to use what Gregg wrote as an idea to tweak and expand. Did the same with most of their covers.

Dickey's instrumentals had the melody and a few changes and the band used those ideas as a starting point. Gregg and Butch said on Les Brer in A minor, all Dickey had was the guitar melody line that they had heard before. Later it was found in a soundboard of Dickey's solo on Whipping Post. A cool melody he played during the solo he just came up with on the fly and it stayed in his head. Apparently the entire band helped Dickey finish those instrumentals. Chuck said he added alot to Jessica as they arranged it in the studio but the melody came from Dickey. Les Dudek says he wrote the bridge and expected a writing credit. But Chuck in recent years made it clear Dickey Betts wrote the song, said that melody and it is all Dickey's song, the rest of us worked out an arrangement just as we would do on a cover song....the rest was the arrangement. Butch felt he wrote part of Liz Reed, the drum part and time signature for the solos. But Duane ruled its Dickey's song and I've noticed on show recordings other than Fillmore East, Duane often says here is a song written by Dickey Betts. On the 1970 Fillmore show released by the Grateful Dead in 1997, Duane says " We are going to start with an original composition written by Dickey Betts". Was that for Butch to hear?

Other songs such as Melissa, Ain't Waisting Time No More, Wasted Words, Come and Go Blues , Blue Sky, Revival, Ramblin Man, Southbound etc are done how the writer wrote them for the most part I understand.

Anyway the ABB has it foot in both I think.

When we went to Madison Square Garden this past March, would anything played and jammed on by those great musicians do? Not to me. I came to hear Whipping Post, Dreams, Liz Reed, Blue Sky, Jessica, Southbound etc.

But I also think Led Zeppelin is both. I want to hear the songs they wrote or stole. I doubt they stole those riffs. I heard some of the originals played in court and it wasn't clearly ripped by Zeppelin to me.