Depends what you mean by the "best". No complimentary shuttle avaialble. I usually take the airport limo - ask for the budget service which costs about RM56. The premier service is just a slightly larger car, costs about RM92. No dif to me, though sometimes with budget you do get a regular taxi instead of the small airport servce cars. The car counter is after customs, before exiting to the waiting area.

Alternatively, you could take the airport express to town, costs RM35. Then take a taxi from the terminal station to JW Marriot. If you do, make sure the taxi goes by meter. Many taxis will try to bargain for a flat fare with you - don't. It's a rip-off.