The pictures of the Parkerized finish on Springfield's website probably aren't the best indicators as to how the finish looks.
Parkerizing is an excellent finish, inexpensive to apply, and very rust and corrosion resistant, especially if you follow the advice of other members and give it a good oil treatment. Contrary to the picture, Parkerizing is actually more of a grey-ish color than it is black, though much of that depends on how much and what kind of oil you treat it with.
Armory Kote, or any teflon-based coating, is also an excellent finish, very rust and corrosion resistant, and has inherent lubricity which reduces overall friction, though oiling is still a good idea.
Personally, I prefer teflon, simply because I'm not a real fan of the rough feel of Parkerizing nor the grey-ish color, which I can never seem to shake off no matter how much oil I try to treat it with. That said, however, I do own a Springfield Loaded with a Parkerized finish, simply because the low cost justified my purchase, and I can get it teflon'd at a later date once I wear through it.