When I first moved to New York, I always took the subway. To my mind, the subway was New York City.
I romanticized it, and even though I previously lived in DC, the Metro just didn't have the same cachet (or dirt) as the New York City subway system.
In my mind, it helped define the city. Cool people rode the subway and everyone else took the bus. Besides, it was generally the fastest way to get anywhere.
Then - four years after moving to Manhattan, and a zillion subway rides later - my friend Jamie got me to take the bus to meet some friends one evening.
One ride on a crosstown bus, and I was hooked.
Why? Well, I discovered what I have always known when I travel: When you ride the bus, you see the city.
The subway - or underground, or tube, or Metro - will get you where you're going fast, but you won't see much on the way. (Although it's good for people watching…but that's a whole other topic).
Oh, an added bonus is that if a bus breaks down, they open the doors and you just hop out. When a subway stalls in a tunnel, best case is that you are just stuck and delayed a bit. Worst case - you have to evacuate and walk along a track while trying to avoid the third-rail.
So, when you visit, you'll want to ride both to get the complete New York experience. But if you want to see the city like a local, make sure you hop on a bus at least once during your visit.