When adjusted for reefers and people, I put them in this order, assuming competence (not perfection) in all,... lighting (coral food), water movement and then water parameters. It is easy/easier for people to get water movement right and most people over do it most of the time - "just add a pump" works for most people. Lighting is harder and a lot of people think that they are lighting their tank well when they are probably deficient in one way or another. Water parameters are easy to get into a competent range, but harder to keep them there constantly. The difference in a perfect water parameter tank and a competent one is not one that I can notice, but I can notice a tank with substandard lighting.
My water parameters can swing quite a bit and nothing notices. I had an alk drop from mid-6 to about 4.0 last year (twice, hangs head in embarassment) and nothing cared when I brought it back up to 6.x with baking soda in about 2 minutes. I do have some of the best possible lighting, though. Alk or other parameter swings did not destroy tanks a decade or two ago like they do now with people under lighting their tanks or using cut-spectrum lighting... this is a pretty new phenonomen in the hobby.