My favorite brushes are Corona. For latex I use Corona "Cortez" and for oil the "Marquis". Both are professional grade brushes and are designed to give a smooth release of the paint. For roller covers I use Kodawool, 1/2 inch nap on smooth walls for latex and 3/8 inch on smooth for oils paints.
There are techinques with brushes and rollers that allow the maximum hide with a coat of paint, but it's difficult to explain in this forum. A "Finish stroke" which uses very light pressure on the brush or roller and is always stroked back into the wet paint gives the most hide for each coat.
Thats about all I can add, Steve and Bob have just about covered everything else.