If you have any elevation change, the best option is ABC/Crusher Run, unless you have the money to pave it. Nothing else packs as well, and in 6 months all the washed stone or recycled asphalt or crushed concrete or slag will be on the sides and at the bottom.
Here's my experience with the various aggregates:
ABC/Crusher Run: Packs well, holds form, has the nasty gray grit when it gets really wet, dusty in summer when really dry, tends to have potholes, but easy to fix. Overall probably the easiest to maintain long term. Cheaper than washed stone, but not by much, but best long term value.
Washed Stone: Best looking, tends to sling to the outside in corners and bottom of hills, does require regular maintenance, but easy to maintain if you have an angle blade or even just a hand rake and some patience. Most expensive.
Asphalt millings: Packs in well, looks nice at first. Over time tends to break down into smaller pieces and no longer holds together, especially in areas where vehicles are turning/starting/stopping. Once is loses its bond, it starts to pump when wet and becomes junk. One of the cheapest options I've used.
Crushed concrete: Breaks down into powder with an end result similar to ABC, not good on hills, but does fine on flat ground. Dusty when dry, slimy when wet. At 2/3 or less the cost of ABC, its a decent option, but last time I quoted it, the difference was about 15% less, so I went with ABC.
Steel Slag: Similar to washed stone, but much higher tendency to washboard. My parents have this on their road, and it could be scraped once a week and it would still have washboards. Other than that its a good top layer, but too loose and too fine to build a base with. Will definitely require maintenance because it drifts out of the tire tracks. I believe its pretty low on the cost spectrum, but I've never quoted it.
Drywall: Can't make this shit up. Guy in Stanley must do drywall work, because he covered his driveway in busted drywall. Was dusty until it got wet, then it was just crap. He has gravel now if that tells you anything haha.
I think the best long term solution is a good 4-6" base of ABC with 1-2" of washed stone on top to pack in and dress up occasionally. That's basically how the driveway in front of my house is (it started with a 2-3" Railroad Ballast base, then 1-2" of ABC, then 2" of washed stone), and it has held up great for years until it sat with snow and ice on it for the past 2 weeks.
@braxton357 and I did a setdown area for an industrial business like this a couple months ago with an 8" ABC base and 2" of 57 stone, and it is holding up amazingly well. They also run forklifts over it, so the areas where they are driving straight are like friggin concrete.
Mid-December:
After 2 months, a couple hundred hours of forklift traffic, and 2 weeks of ice/snow:
