Flex at the 93 AC was amazing, but had flaws.
Personally, I think there are THREE "best ever physiques" that are pretty much right up there in terms of overall greatness (but each has their flaws)/
They are (in no particular order):
Shawn Ray (1994 Olympia - perfection except for lats
Ronnie Coleman (2001 AC or 99 British Grand Prix - also amazing, except for calves and abs)
Flex Wheeler (1993 AC- pefection as well, except for lats (and calves).
I don't think bodybuilding has a definitive "best ever physique".
There are several contenders (like the three I posted above) but to pick one is totally subjective.
here are some pics:
Shawn, 1994 Olympia:

Ronnie, 2001 AC:

Flex, 1993 AC:

Its interesting to note that although all 3 had (glaring) flaws, the rest of their physiques were SO DOMINANT that their flaws were almost an afterthought.