There is a lot to consider when selecting tires. Obviously performance and price are at the top of the list. . Also, you are not thinking just about 1 set of tires, but about how many you'll need over the course of a season. Or more accuratly, the equation: Performance/Price*Number of sets=Budget.
Once you figure that out, you have more to consider. Performance is an equation in itself. Have you considered why say a Bridgestone is over $100 while a Metzler is around $60? The difference isn't so much in tread patterns or availability of soft/medium/hard availability. It is not the "name brand" or because Bubba or one of the Ryan's use it. It is the weight.
Tires sit out there on the "unsprung" end of the suspension. ALL weight out there is bad for both handling and the amount of work (Hp) your motor has to turn. Unfortunately, tire weight is not an advertised data point. You'll have to measure those weights yourself (that would be a great website idea! - anyone?).
Finally, you have to select the proper tread pattern/survivability for your terrain. This is also tricky because different tire companies advertise different information. When Kenda or Mitra say it is a Soft tire, is it a soft rubber compound or for soft terrain? Soft terrain uses a HARD compound while hard pack uses a SOFT rubber. Note that soft rubber wears out faster.
The last thing to consider is tire inflation. This doesn't go so much into what tire to select, but something to consider when evaluating different tires. Some might like it a little softer/harder than another. Pro riders pay a lot of attention to the front tire. Some have an almost insane amount of feel for them and 1 lb of pressure either way will ruin their event.
While this didn't tell you what tire to buy, I hope it help you determine which will work best for you.
One last thing. Loose gravel, depending on the depth could be considered hard pack or soft pack. Sand is usually soft, while rocks also depend on their packing. Do you ride ON them or do you THROW them. ON is hard, while TROWN is soft.
