Off top of my head...
LG LVB418 - Faroudja
Samsung DVD-HD960 - Faroudja
Oppo 981HD - Faroudja
Yamaha S2500 - Faroudja
There were previous versions of the above models that upscaled to only 1080i.
Oppo 983HD - Anchor Bay
Denon DVD-2930/3930 - Realta
Toshiba XDE500/600 - XDE - made the good mastered DVD, even better (almost HD-like) and the bad mastered, even worse (amplified the flaws in PQ).
I thought the players with plain old Mediatek chipset were fine upscalers, especially Philips 5990/5992 which pretty much played anything avi.
For DVD playback, I think current blu ray players are not as good as above mentioned DVD players with the exception of handful like Oppo.