I think I bumped into this series around... 2010, it was Last Order, I read it like I was possessed, the incredible art, the amazing world, the charismatic characters, the philosophical questions, and the fights... GOD... THE FIGHTS, this series destroyed my sense of taste in fight choreography and rebuilt it from the ground up, I could never look at some of the things I love before with the same eyes, and since then... very few stories have the same level of martial arts integrated with special powers and fight choreography.
Then I went to read anything I could find of Kishiro-sensei, especially the first series, actually... there is a funny story to that, I read Gunm Last Order first, I was new to manga still at the time so I didn't know how to search things or judge when a story had a "prequel", so I went a lot of time without knowing about that, then when I searched more about Kishiro-sensei I found out about BAA, and at the same time... I found out that during the time BAA was being made Kishiro-sensei had a very serious health problem, so serious that he was certain he wouldn't survive, so unfortunately at the time, he had to rush things up and made a "first series" only finale.
It was a good finale, rushed without a doubt, but it had a good emotional core to it, but now... it was around that finale that we had the first appearance of Alita's master, someone that we now know is actually some sort of "spiritual" overmind... Kishiro-sensei had a lot mapped out even more than 3 decades ago.
Fortunately, he recovered and went to do BAA:LO, and the finale was "discarded", and LO starts right after Alita and Nova's last confrontation on the surface of Earth.
I presume those problems still come now and then and that is why this series has such a "scuffed" schedule, but like I said... and especially now considering the names we lost in recent years... I prefer to wait, in a way, just having this story and the ones before is already a miracle.
By the way, I recommend looking at Kishiro-sensei's past works, there is a one-shot about a Motorball player that is VISCERAL, and the BAA Gaiden has some cool, funny, and sad stories about the people on earth.