Since the OP didn't ask for security chief, I'm a fan of Ensign Garrovick.
I think Worf was the model of how to bring the position to the fore effectively, as held by a recurring character. I voted for TNG Worf.
I always thought that Odo's position as security chief was wildly implausible. For one thing, I never believed that the Cardassians would have trusted Odo as chief, during the occupation. For another, nothing suggests sleeper agent like Odo's background before he was named "Unknown Sample" (i.e., it's completely unknown). Given that, I never believed that Starfleet would have approved of him as security chief. Command would have insisted that Odo be replaced, which would have gone relatively smoothly, given that Odo's immediate superior in security would have been withdrawing with the Cardassians anyway. However, Odo was always an entertaining character to watch, and no doubt would have been formidable in his position.
I think Worf was the model of how to bring the position to the fore effectively, as held by a recurring character. I voted for TNG Worf.
I always thought that Odo's position as security chief was wildly implausible. For one thing, I never believed that the Cardassians would have trusted Odo as chief, during the occupation. For another, nothing suggests sleeper agent like Odo's background before he was named "Unknown Sample" (i.e., it's completely unknown). Given that, I never believed that Starfleet would have approved of him as security chief. Command would have insisted that Odo be replaced, which would have gone relatively smoothly, given that Odo's immediate superior in security would have been withdrawing with the Cardassians anyway. However, Odo was always an entertaining character to watch, and no doubt would have been formidable in his position.