You are looking at a $5000+ difference in price, and 2 very different cars:
Accord - FWD, slower, better MPG, cheaper to insure, probably a little roomier, rides better, does not handle as well, possibly a little more refined and quieter, cheaper, better every day driver
Infiniti - RWD, faster, better handler, more $$, more to insure, stiffer ride, noisy when revved, better for a lead footed and aggressive driver
If you can find a G37 that is not optioned to the hilt, and can keep it around 35k, I would lean that way. Might I suggest a BMW 135i. It is about the same price as the G37 if you can find one without NAV and iDrive and other add ons. Will outrun and out handle the G37, and has a paid for comprehensive maintenance package. It is a little on the small side though.