I have a couple really close friends who haver played for years. I only started playing with the Anniversary edition, but what I found fascinated me. Yes, a great many zones were closed to me, as the requirements of having a raiding guild at my disposal were too much at the moment.
I voted Serpents Spine, because it brought back the group. Zones, missions, quests, items, rewards, and ADVENTURE for all levels. I think SOE hit it on the head with this expansion. Granted, I'm not speaking from an old-eq'r viewpoint (I was still playing tabletop and miniatures- the REAL old-school gaming), but fro what I've read, what I've seen, and what I've been told, I couldn't have joined at a better time.
And to solve the "problem" of not seeing old-world content, I simply created my OWN guild, to go through that very content, so all can see where great events took place.