What criteria should one keep in mind when choosing oscillators for use with fpgas?

In addition to what ak6dn said, these days it often makes sense to use a clock generator like one of these from Silicon Labs:

https://www.silabs.com/products/timing/clock-generator/si533x/pages/si533x.aspx

These chips can generate up to four clocks from one reference, and each clock can use a different signalling standard. Very low jitter, and you can reprogram the clocks at any time. We've been using the Si5338 for years. Great part. They're used on some of the newer Altera dev kit boards.