The middle, but I doubt it could ever have come close to infiltrating the big two (or three or four) or whatever.
U2 (and those close to them) never talked about being innovative or necessarily different with HTDAAB, they were always about just coming up with some great rock-driven sounds and adopted a back to basics approach.
So messy were the recording sessions leading up to the album, with the whole Thomas saga and carryover from ATYCLB, that 11 songs were slapped together. The songs themselves hold up pretty well when taken on their own (Vertigo, SYCMIOYO, COBL especially), and do seem to adequately achieve what U2 were trying to do with the particular songs at the time, yet any album-orientated focus or cohesion could never really eventuate.
U2, and I think most will agree, are at their most unbelievable when they are at their most visionary, when they have a clear idea of what they're trying to do, what mood they're trying to capture, and it is something they so famously achieved on JT and AB. From all reports, and despite the misadventure with Rubin and the 5 year wait for NLOTH, the new album seems as if it's being delivered from a U2 who are very sure of where they are at and what they're trying to do, there seems to be less confusion and haste, which bodes well if we anticipate a 3rd (or 4th or 5th) classic.