I like krylon semi-flat as far as color goes, but I am horrible with a spray can. I can not get an even coat.
Last time I used a roller and I am pleased with the results. I cant remember the name of the roller, but it is not your dtandard one. It was smooth foam. It applied the paint very well and did not leave any streaks. The paint I used was black eggshell. Not quite flat, but almost.
Greywolf once suggested that you apply a clear coat to the cab over the black paint while it was still wet. I have not tried this yet, but he said it makes a nice even finish.