I agree that Code 83 looks a bit more prototypical...if you get down to track level and concentrate on the track alone. However, Code 100 isn't all that bad, and may have some advantages in operational reliability. That said, I am using Code 100 for my current layout simply because I have been in the hobby off and on for about 57 years, and have a lot of track (both nickel-silver and brass!) plus turnouts galore that I have reused over the years. On a couple of sidings and a Walthers 90 ft turntable, I have Code 83.
Starting from scratch, I might have gone to Code 83. If you should happen to pick up some older AHM locomotives, rolling stock, etc, with the oversized flanges on the wheels, then Code 100 is your best bet.