DS9 isn't my favorite Star Trek series and I prefer Worf, as a character, to Odo. I still think Odo is the best security chief.
"Hippocratic Oath" is proof that Odo is better at the job than Worf. Worf also embellishes about how much better security was on the Enterprise when Odo calls him on it in "Bar Association". I could list a whole slew of episodes that showcase Odo's great investigative skills, "Improbable Cause" just off the top of my head right now, and I can go further if you like but I don't feel like typing so much right now.
I personally like to judge how well the characters do their job based on what I see and how they handle different situations. There are a lot of factors. As if I were a boss, evaluating employees.
I won't deny that there are people who confuse "best" with "favorite" and treat it like a popularity contest, but I'm not one of them.