UL will say it's suitable. However I guess the issue of what type of wire vs. type of connector also hinges on what is easier to work with a particular type of terminal.
For instance, when it comes to screw terminals (like those found on wall switches and receptacles), solid is easier to work with once you've got the hook done. You don't have to worry about individual conductor strands coming out from under the screw as it tightens, like it happens when attching a cord cap or a lampholder to a piece of lamp-cord.
When twisting two conductors and attaching a wirenut, stranded is easier because you can twist it partly with your fingers - you don't need a linesman's pliers.