Great Final Fantasy dungeons:
- Ultimecia's Castle (FFVIII)
- Deep Sea Lab Research Center (FFVIII)
- Via Infinito (FFX-2)
- Pharos (FFXII)
- Giruvegan (FFXII)
- Henne Mines (FFXII)
- The Leviathan (FFXII)
- Tomb of Raithwall (FFXII)
- Barheim Passage (FFXII)
- The Stilshrine of Miriam (FFXII)
- Feywood (FFXII)
- Fanatic's Tower (FFVI)
- Daryl's Tomb (FFVI)
- Phoenix Cave (FFVI)
- Kefka's Tower (FFVI)
- X-Death's Castle (FFV)
- Tower of Zot (FFIV)
- Tower of Babel (FFIV)
Can't remember specific dungeons from FF1-3, 7, 9, 10, or 13.
Of course, FFXII has the best dungeons AND locations.
Paramina Rift

Ogir-Yensa Sandsea

Nam-Yensa Sandsea

Cerobi Steppe

The best FF.