Currently every single "big" game has a bigger art team than programmers team. The opposite is now quite scarce.
See
http://www.dis.uniroma1.it/~catarci/...les/Games1.pdf for examples (slides 18-22), teams goes from 1 part time artist in a 5 person team (1988) to a 2003 game with 50% artist, 25% designers and 25% programmers. That was 10 years ago, and the trend hasn't changed since then.
Current state is around 50% to 80% art I'd say, and 10% to 25% coding (and can certainly go under 10% for AAA games).
But then, none is "harder" than the other, it's so different you can't compare both overall, but maybe only on specific points. For example a bad programmer can quite easily hide some of his ugly code, as long as it works (unless it's on critical parts of the code), while an artist can't do ugly work, this won't go unnoticed.
Competition is harder on coding side, there are so many people who want to work in game dev. If you're bad (and not willing to work much more than what you'd do in other areas), you're out, it's simple as that.