Life will be better for you as a Corpsman in the navy, granted you don't go FMF. FMF Corpsman are Marines who get paid by the Navy. The Marine Corps does not maintain its own Medic Corps, and as a department of the Navy, uses Navy Corpsman (FMF Corpsman) for that role.
Life in the Army is hard because of their current involvement in the war effort in the Middle East. You will MOST LIKELY do a tour in Iraq or Afghanistan as an army medic.
As a Corpsman, you MAY do a tour in Iraq, but if you are stationed on ships or whatever, you'll eat better, sleep more soundly, and enjoy better travel benefits than the average soldier.
Still, if you're interested in being a war hero or in contributing directly to the efforts of the service members in theater, you can still do that in the Navy as an FMF Corpsman. The quality of life is just better, in general, for sailors from my point of view.
Good luck and thanks for wanting to help.
EDIT: Actually, FMF may not be open to Females. I'm not sure. If you want to go to war, Navy may not be the best for you in that case. If you don't want to, that should pretty much make your decision for you.