Design outweighs materials for me. For example, I think one of the best folder designs out there is the Spyderco Calypso family. If the design was available only in AUS-8 and FRN, I'd still want one. Fortunately, they're available in VG-10, S30V (the UKPK is part of the family), and ZDP-189 with G-10 and carbon fiber. And I carry and use a couple of Calypso, Jrs. even though I'm not all that hot on FRN scales.
Another example is the Boker Subcom and kin. FRN, AUS-8, but for small knives they are incredible. If the same designs were available in G-10, Ti, and premium steel, I'd be all over them.
Of course at a certain point materials could be so poor (like 420J2 or worse blade), I'd pass on even a great design. Haven't seen that yet. As another poster suggested, great designs and good materials usually go together.