jlg6184: That seems to be what I am hearing from friends as well...I loved SOC, beat it 3 or 4 times with and without mods, but I thought Clear Sky was abysmal. Broken features and bugs were too much for me, and the feel was just too different.
COP I've heard is the most cleanly programmed -- little or no bugs at launch, and improved further since.
Here's a nice summary from the
Steam forums:
"Gameplay wise, one could argue this is the best game in the series it takes the best of the previous two games and throws most of the bad out the window. Graphically this is the best game in the series. Gone are the hoards of people from the zone, replaced by a moody atmospheric environment full of hidden treasures and dangers. Returning is the upgrade system and new artifact hunting system that Clear Sky introduced. This could be the ultimate stalker experience."