Do you have any settings that you like that have systems that you dislike? For me, it's Dark Sun. I really like the dying earth, mad max/dune feel, the intrigue, and the interplay between psionics and magic, and the stark beauty of Athas itself. I like the takes on the races and cultures, and the detail that went into the tablelands.

I'm not the biggest fan of DnD however. While the cosmology per planescape is neat, I find classes to be restrictive, even with multiclassing, and the large focus on combat mechanics and the comparative lack of social mechanics leaves a lot to be desired, comparatively speaking. I also feel the d20 is a poor choice for a universal die given the flat 5% chance per side. Right now I'm hoping to try a different system, though I'm still unsure if I want GURPS or something that is still universal but less complex like BRP.