you may want to call a few reputable tire shops and ask about the tires, which they would recomend and what their customers think after they have been installed.

Most tires made now days are solid and dependable, a result of a lot of competition.
Harder tires disapate heat better and as a consequence have a longer tread life. On the other hand the ride and handling is not as good. Soft tires give you better grip, and in many cases a smoother ride, but come at the expense of longevity.

You may want to consider how you use your van and what sort of driving you do. If your regular commute is short and has a lot of stop and go, the softer tires might work better, as they heat up more quickly, for longer commutes the harder ones may give you better treadlife since they heat up much more slowly (heat and friction are the main destroyers of tread)

Either way just make sure the shop does a proper job installing, balancing and aligning the tires, be extra attentive after you drive off. Make sure to inquire about free balancing after you purchase.