I think Neverwinter Nights' big plus point for me was, certainly at the time, I felt it was the complete RPG package. It had single player, multiplayer, a fairly easy to use editor (and mods have become so important in prolonging the life of RPGs) and a DM client to return to some of the 'feel' of traditional P&P RPGs. Now the engine looks rather dated and raggy round the edges and it's interesting to see in The Witcher what the engine looks like without the tiling in place.
PST I loved, and that's probably my favourite RPG, just because of the way it fleshed out all the characters and the immersive world. Having said that, I lost a lot of sleep to Diablo 2 and that game always hits a certain sweet spot than no other game has done in exactly the same way.
