Best Bibimbap in Manhattan
I'll second Gahm Mi Oak. I lived on that block for a couple years, and they were always good. Also solid was the big garish place a couple doors down - Kum Gang San - though I know they're a more "controversial" choice, and have a few detractors, perhaps because of their popularity. I like the banchan (the assortment of extras they bring out to accompany your meal) more at KGS, although the Kimchee is higher quality at GMO. Seems the crowd is leaning GMO's way, though.
One thing to make sure is that you order the "Dol Sut" (or "Dol Sot") BiBimBap - that's the version that comes in the hot stone bowl, leading to crispy rice goodness. Regular BBB just comes in a regular, not-hot bowl.
Kum Gang San
49 W 32nd St, New York, NY 10001
Gahm Mi Oak Restaurant
43 W 32nd St Frnt 3, New York, NY 10001
surprisingly I think the best bibimbap is at gam me oak (a suh long tang specialist), they only have a few dishes on their menu, but their classic bibimbap is def the best in ktown (i eat in ktown alot, been to every restaurant)
the kimchi dolsot bibimbap at kunjip is also very good (although its quite a different dish than the classic bibimbap)