A broken record here, but here's another vote for either:
1) Rancho 9000's - if you tow varied loads and run empty, too. They simply allow you to dial in the level of stiffness required for your conditions.
2) Bilsteins - if you don't feel you need adjustability but do demand quality & consistent performance.
I've had huge loads (well, for me 22,500 Gross on a SRW 2500 4x4) that felt scary but dialed 'em up to 8 or 9 and confidence returned. Hard to put a price on that.
One time I unloaded all the weight, forgot to dial 'em back to 3, and went flying down our rutted dirt road.
WHOA ---3 broken teeth later... ... point is, the adjustment really makes a difference. It only takes all of 30 seconds to change 'em.
On our Ram Van B 2500 I run the heavy duty Bilsteins (not sure if its the exact part # for our trucks, I guess it may be) and they're great. I went with them because I was curious to try Bilstein quality and am NOT disappointed.
Very nice ride, not rough but firm & superb handling (for a van).
I did tow a heavy U Haul recently with this van, and was wishing for the adjustability of the Rancho's, like our Ram truck has, but overall it was fine.
Us TDR veterans have heard this discussed for years on these forums, [and not to knock any other choices that may also satisfy], Rancho 9000's and Bilsteins are the top 2 choices.
My . 02 anyhow... .
Regards,
David B.