An old school reply: I am always comfortable with a USGS 1:24000 map. The topography is absolutely correct, although the cultural features may be considerably outdated. If I don't know the area well, carrying an additional USFS map within national Forests is a good idea, because their depiction of roads and trails is more current. I have several vintage USFS maps of areas I like particularly; they are useful because they depict abandoned trails and he like. For paper maps, the National Geo maps are great; they use the USGS topography and run good field checks to insure accurate trail placement.

If you want real precision, nothing beats a recent aerial photograph, used in conjunction with a good topo.