We fly out of Buffalo a lot. Jet Blue and Delta are our airlines of choice. Especially to the Caribbean. We, too fly out of Pearson in Toronto but lately just for cross Atlantic flights to Europe. When it comes to least expensive you simply have to do the leg work regarding what time of year you are going, what days of the week you are open to flying, and so on. Buffalo/Niagara International is a medium sized airport that has some nice advantages. Park, Sleep & Fly hotels are literally right across the street form the terminal. You can cross the street at the traffic light and you're right there (or catch the hotel shuttle). Another advantage is that BUF is not too large nor too small which means there are no sky trains you have to catch with all departure gates conveniently located. While some airports have turned into glorified shopping malls with gates that are hard to find, BUF is a simple but efficient airport that has always served us well. Most recently we flew BUF to ATL to SXM and back with Delta and everything went perfect each way.

Quick note that back in March they were doing some exterior construction improvements to the main building and the droop-off and pick-up zones. So, you may want to inquire directly with the airport to check on the status of the construction and if they recommend allotting additional time when flying to and from here.