Season 3 isn't that bad.
There are some clunkers, but Seasons 1 and 2 had some clunkers as well.
'The Enterprise Incident' has to be my favorite. And, yes it's because of Joanne Linville.
She oozes sexiness, toughness, and respect.
Commander Tal is one of those Romulan characters that add to the mystique of said race. Just the way his character is lit, the way he's filmed, and the mannerisms adds to the mystery and exoticness(?). Hell, even the curly hair seems to be something applicable to Romulan males, like the bowl hairstyle is to Vulcan males.
Overall, what 'Amok Time' and 'Journey to Babel' did for Vulcans, 'Enterprise Incident' and 'Balance of Terror' did for Romulans.
I hated how they - the Romulans, and even the Vulcans - were changed during the Berman era. Giving props to J.J. Abrams, his Romulans were a bit more 'alive' (especially after the depictions in the Berman era) and we even saw a long-haired, blonde Romulan woman (e.g. Nero's wife, albeit a small recreation). The Romulans actually looked and were mysterious and sexy...rather than weird, stiff, boring.
I'm sure there are others from Season 3 I like. For instance:
*For the World is Hollow and I Have Touched the Sky. (A good McCoy episode, and great music for that particular episode).