Both are absolutely perfect for different reasons.
I know this is kind of a cop out, but I've always had them in a tie at the top because they are just too different to rank fairly.
Even looking beyond what The Panther asked for, which is to stick to studio albums only and ignore everything else, I can't break the tie. They will both be remembered as vital to U2's legacy- JT for being quintessential U2 that put them in that exclusive tier- AB for being a stunning, likely unprecedented reinvention for an act of that stature. Both tours were iconic- JT for the overnight superstardom and nightly buzz and Zoo TV for the obvious.
I guess if I Iook at my personal experience as a U2 fan, I can say that JT was more immediate by a little. I grew up with all the hits as background noise. My Mom and aunt were big fans, but I never paid much attention to them until ATYCLB. Became a big fan after the Super Bowl halftime show. I'd never heard Streets before and thought it was new. Haha. I think I discovered JT right after that. I obviously knew Still Haven't Found and WOWY but couldn't place them on an album until then.
When I really got into them, after HTDAAB, I wanted to go over the back catalog. JT got better and better, whereas AB, I just remember doing enough research to find out it was the album Mysterious Ways and One were on. I distinctly remember my Mom playing AB a lot in this time and thinking "okay, good, but where's JT?" Only Whos Gonna Ride really stood out to me. The entire album clicked for me and never looked back only after I saw the ZOO themed encore on the Vertigo Chicago DVD and got on an AB kick after that.
Ever since then, around Christmas 2005, I've been unable to pick a favorite personally or come up with a less personal way of saying one is better than the other.
They're the masterpieces for a reason. Pretty undisputed at that. The only real discussion I've ever heard from fans or just music people in general is over what should be #3.