Having been a reefer (well- of the marine sort anyway) for only 4 short months- I voted Instant Ocean regular. I chose this only because it is readily available locally at more than one location.
I used Kent for a while and then switched to IO because it had a good reputation and is considerably cheaper than Kent in my area. Both are good salts - never had a problem with either one. I'm tempted to try the new Oceanic salt mix; lots of folks have good things to say about it.
Oh, and by the way, after reading the article I am switching from IO to Crystal Seas. And its cheaper than the IO at the LFS, even after paying shipping.