Straight out of college? Most banks are biz casual these days, but you'll still need to have a suit or two on hand. Assuming you have the standard recent grad budget, go with something basic like Brooks or J. Press. If you'd like something better, maybe check out MTM / custom suits from Ned or LS Mens in NYC.
If you are in a biz casual environment, invest some money in decent, well-fitting shirts and 3-4 pairs of nice trousers in sturdy cloth and basic colors. And naturally 2-3 pairs of good shoes. AEs are popular around here as quality shoes at a (relatively) affordable price. Stay away from Magli, Ferragamo and the like.
I wouldn't spend too much $$$ just yet as your tastes, weight etc. will evolve quickly over the next few years.
Also, do a search - many questions like this are posted on a regular basis.