and what is the best the PAL version OR NTSC/US ?
IMO the PS3 60GB NTSC/US is the best because it has PS2 backward compatibility by hardware (same as the PS3 20GB), but they are discontinued. The PS3 60GB PAL and all the 80GB models use emulation (that means that some PS2 games have issues). The "40GB" models (PAL or NTSC) do not play PS2 games.
If you will use PS3 games only, both models are ok. The major difference is in PSX, PS2 and DVD movies that are region locked. So it depends what is your region... and what is the region of the media available in your stores.
I have a NTSC console (but stay in a PAL region) mostly because the PAL console goes for almost twice the price here as in the USA. Region free means not having to worry about games, and BR movies are cheaper on Amazon in any case
So if it's cost saving, the NTSC for me was the better decision.