I think once you're hitting the level of "one of the biggest cities in the world" there's almost guaranteed going to be really awesome cuisine. I thought Paris had really great food when I was there, I'm sure Tokyo's got delicious offerings as well (I love Japanese food, mmm).
I just moved to NYC, though, and the food options here are incomparable to anywhere else in the US I've been. (Note: I haven't been to San Francisco, and while I'm sure it has good food too, NYC's excellent transit system means I have wider access to places.)
I'm continuously surprised by how CHEAP things are, too! Yesterday I paid $1.50 for a box of strawberries, $0.75 for some cherry tomatoes, and $2 for a sizeable package of freshly chopped and peeled kiwis. (In the midwest, I'd pay almost that much just for the strawberries.) To top it off, I had the best lamb and rice meal I've ever had...for $5 from a halal food cart. (I actually spent an hour today looking for the cart again, I liked it THAT much, but it was nowhere to be found. I will look again tomorrow!!)
Of course, I still haven't found anywhere that sells a gallon of milk for less than $4, but I'm going to keep searching. I kind of enjoy exploring places and mentally marking down which place has the cheapest offering of a certain thing.