If you've got a tv with DVI or HDMI inputs, I would suggest the Oppo, as it's got a great pic quality and does the conversion flawlessly. I know lots of players are said to do the conversion 'flawlessly' but the tests on the secrets of HT site show the Oppo actually does it. Added bonus if you've got a digital TV that can display either PAL or NTSC, because then with a player like the Oppo, no conversion is even necessary.
Again, I only suggest that player if you have DVI or HDMI. Analog inputs look fairly bad from it, if that's all you can use.
Most region free players do a decent conversion now, and there are so many in such varied price ranges that it's a lot like trying to shop for your regular DVD player since the selection and quality is there. HKFLix has a nice, albeit expensive, selection; and videohelp.com lists almost every player made, with ratings and whether or not it can be hacked to multiregion. Those are some places you might want to start looking at.