Nelles Maps are the best foldable maps for travelers I’ve seen. I favor them for six reasons: 1) They come at a good practical scale for traveling, fine enough to show most small rural towns. 2) Each map displays shaded physical relief of mountains, highway numbers and even “places of interest” – which are often not listed in guide books. 3) The maps are printed on both sides to maximize coverage. 4) They are printed in a form that folds neatly into a shoulder bag, with cover. 5) They are reasonably priced. 6) Best of all, Nelles seem to keep them very up to date. I haven’t found any Nelles maps in print that are more than a few years old.
These qualities may seem expected, but most maps of third world countries are uselessly vague. Nelles maps shine in particular for Asia and Africa, and remote places where good maps are hard to find. I know from personal experience they have the best ones (in English) for China (in 3 maps, a North, Central and South), for India, and for the Himalayas as a whole. And they have the only useable map for Papua Maluku (Papua New Guinea) that I’ve been able to find. You may be able to find maps that are better for specific countries, but try Nelles (based in Germany) as your first stop.