It depends on the wiring method, the conductor insulation and the temperature ratings of the connections. For NM cable you would use the 60? C column. For THHN in conduit you would almost always use the 75? C column.
Those ratings are very important. As Rob said, 75? C is usually ok, but you need to verify that the device you are connecting to is rated that high. Looking at a Leviton catalouge, some common duplexes (5362, BR20, or CR20) are designed for 60? C max continuous, and many switches for 65? C.
The rule 110.14(C)(1) requires us consider wire smaller than 1/0 at 60? C unless the termination devices are marked otherwise.
So 75? C may usually work, but it is your responsibility to show that when using small wires.