mine would be my (shared) copy of the Lunatic- Art edition. Really my Mum's (Pathwalker) but mutual. Way too big for me, more framable pictures than cards, in my opinion
The portfolio edition of the Lunatic Tarot is my largest deck. Out of decks I actually use it would probably be the Far Sight Tarot measuring 3.62 x 5.91 inches(9.20cm x 15.00cm)