I have tried a lot of apps, and I really like mapmyride.com for route building and GPX export, then Backcountry Navigator for off line maps (clear winner for adding a mix of vector road data, too maps and imagery. BN doesn't do turn-by-turn navigation though, so if you meed that, Osmand is my recommendation. Note that both off line gps apps work with a wonderful opensource for pcs/macs called Mobile Atlas Creator which takes all the work out of downloading raster maps (topos, aerial/satellite imagery).