I really liked FarCry, up until about half way through. After that, it just got more and more boring. And then a bit more boring. I finished it for the sake of it, and not because I was at all interested in what was going to happen next. The final few levels were a complete joke, and the cutscenes were worse than terrible.
I quite liked Doom 3, I think this is because I always played it in the dark with headphones - you had to get really into the game for it to 'work'. There were a lot of good features, but the whole thing got very samey. The end boss was so easy that I don't think I took any damage on it.
HL2 never stayed on the same thing for that long, had a good variety of settings, and had some very good ideas put into it. I would say the graphics engine for HL2 is probably the simplest of the three, but to me it is the most effective in implementation. It is definately the only game of the three where I didn't really know what was coming, and that was at all creative with the gameplay.
So between these three games, I think we have really proved that amazing graphics by themselves don't make a great game

Also, even though all of these games have what is supposed to be a great physics engine, only one of them used this to make any difference to the actual gameplay.