KYB = Kill Your Back
They ride stiff when new, like shocks for a car, they fade out fast when being worked on a rutted road or carrying speed on forest roads.
Bilstein = great ride, fantastic response, longer travel, lifetime warranty!
You can buy 2 sets of KYB's for what you pay to get a set of Bilsteins, but... you'll buy 2 sets of KYB's before the bilsteins show any sign of wear and if they do... lifetime warranty.
to me it's comparing economy replacements to performance replacements. If you're building a capable vehicle for off road and expedition use; Bilstein, if you're just daily driving and rarely or never going off road, the kyb will work just fine. This holds true for trucks and cars, the DSM's of the old days (90-99) had KYB and the EVO's came with Bilsteins. The evo was an out of the box 'race car' so it was equipped with the good stuff, brembo brakes, recaro seats, momo steering wheel, enkei wheels and... Bilsteins. The DSM's were turbo economy sports cars, so they got middle of the road daily driver decent stuff. Both will yield good results, it all depends on how you're planning to use them.