There is no best. Several current and not so current sims have their
merits. Currently I have three on my computer:
Papyrus's Nascar 2003: hands down the best driving feel for me. I can
really tell what the car is doing and even if I were to stick with the
lumbering Nascar stockers, it's still great fun to throw them around the
road courses. It's GPL, but with grip... and I have a weird timing bug on
my notebook which prevents me getting GPL to run properly without going into
slow motion.
Live for Speed: great value for the buck. The tracks, while not real-world,
are really nice looking, and there is an interesting assortment of FWD, RWD
and AWD cars. The physics model rates up there with the Papyrus model in
terms of the feedback coming through the controller. The only thing that
spoils it for me is the frame rate dip with lots of cars on the screen.
Rally Trophy: a bit of an oddball which not many consider a true sim, but I
love exactly the cars modelled here (Lancia Fulvia etc.), I like my rally
action to take place at a bit less than warp speed, the physics model is
acceptable, the graphics are (I think) great and it's just a lot of fun. If
you want "easy to use" and "entertaining", I don't think you could go wrong
scouring the bargain bins for this one, add some new cars, patch it and go
driving. After a long pause I reloaded it on the weekend and blew away 4
hours and was grinning the whole time.
Stephen