Link- Same question by another poster
Current voting in the linked thread is...
R9500Pro: 73 Votes
GF4 Ti4600: 14 Votes.
My opinion... R9500Pro.
Fully DX9 compliant, vastly superior vertex/pixel shading performance. Fairly similar 3D performance, except with FSAA or Anisotropic filtering in which is manhandles the Ti4600.
Consistently decent 2D quality, much better DVD playback implementation, and a far better TV-Out implementation on the driver level. Slightly worse multi-monitor implementation on the driver level.
No real point saying anything more as you can find tons of opinions in the linked thread.