Other than Operation Metro, I cannot really think of a "bad" Battlefield map. Then again, I don't play Battlefield that much. Would the competitive maps from Hardline count since they're just segments of the larger maps that are too big for 5v5?
I hated most of Battlefield 4.
In Battlefield 1, Heligoland Bight was genuinely awful.
I’ll say, of Battlefield 1, every map in vanilla justifies its existence at least somewhat. Some I don’t really enjoy gameplay wise (Fao Fortress, Empires Edge, Argonne Forest), but even those are beautiful aesthetically and are functional.
Every single map in They Shall Not Pass is goat.
Galicia is goat, Lupkow Pass is great, Tsaritsyn is an acceptable clusterfuck, the rest of In the Name of the Tsar bored me.
Zeebrugge and Achi Baba are good, Cape Hellas is acceptable, Heligoland Bight is FUCKING TRASH.
Passchendeale is good, River Somme and Caporetto were ugly and boring piss.
The peak of the series that I played (BF3 vanilla, BF4 vanilla, BF1 in its entirety) was They Shall Not Pass.