As the previous owner of a Nevada Silver 1971 Monte Carlo SS 454 and the current owner of a 1969 Grand Prix SJ I'd say the GP by a nose because of the unique interior and the better ride. But the Monte Carlo was awesome too and I'd love to have another one some day. Below is the link to Bills 69 SJ and a old pic of my Monte BITD.
https://www.yenko.net/forum/showthread.php?t=112043