While Nissan doesn't really lead the pack in any one category (reliability, affordability, design), it's a solid performer in each. Nissans cause their owners fewer problems than many other manufacturers' cars, and outsell Volkswagen, Subaru and Honda.
Most Nissans boast high safety standards, though some current Micra and Patrol models fall well short of 5-star ratings. So if you plan on buying a secondhand Nissan, research its safety rating on top of the usual used car checklist.