Much to my surprise, as I'm aware I'm usually a bit more conventional - even, dare I say it, square - about these things, it was this tiny experimental garden from Rebecca Butterworth, Victoria Pustygina and Ludovica Ginanneschi which for me beat into a cocked hat all the bells-and-whistles big show gardens and even the quirky Henry VIII's Wives gardens (not sure jawbones will catch on as garden ornaments but you never know).
The thing I liked most about it was that as you approach, the mirrors create the illusion that the planting is stretching away underneath the ground like some subterranean cavern. It's a truly lovely effect.
The planting was fabulous too - all big gorgeous colocasias (alocasias? never could tell the difference) and the slender elegance of Cyperus alternifolius: there were some very understated hemerocallis in there too in just the right shade of dusky pink and butterscotch. It was all beautifully well-judged and deservedly won not only a gold medal but also Best Conceptual Garden.
The garden has a painfully pretentious official write-up - presumably originating from the designers themselves which is mildly worrying - but I got around that by not trying to 'understand' it too much. For me it worked simply as a small but exquisite little piece of planting heaven.