Third Ave Midtown. If you go to the back, the bagels are almost always hot from 9-10am
You can ask for a dark one.
Get butter from the cashier in the front -- so you don't have to deal with the bitter, career butterers.
If it's so hot that you burn your hand cutting it open -- and that the hard exterior starts to shave off onto your desk -- they are usually the highlight of my work day.