Denso are OEM and are better than NGK's.
$80 every 120000 miles is nothing - c'mon
Maybe it varies by specific 4th gen model year, but the 2k3 owner's manual specs both NGK and Denso parts as OEM. There have been plenty of reports of half-n-half V-6 motors in both 3rd and 4th gens; can't remember for sure if I've seen any V-8 owners confirm NGK/Denso split motors. I'd have no problem going with whichever's easier/cheaper to get.
Spark plug type:
1GR–FE engine
DENSO K20HR–U11
NGK LFR6C11
2UZ–FE engine
DENSO SK20R11
NGK IFR6A11