I’d go for Orange County.
It was the first of its kind. It is worth starting from the beginning for various reasons.
The “quality” of filming makes it look so old! Amazing to see how much tv filming has come on since then.
The fact that it was so new - there are no “pretences” due to being on camera. The clothes are shit, they don’t care what they say/show.
You need to see how each character progresses as the seasons move on. Both in character, wardrobe and cosmetic work! Plus the dynamics.
if you’re looking for something a bit shorter, then it’s worth trying Melbourne. Love it for the sunshine and the characters.
And, if you’re looking for really short, then do Sydney. Only lasted one season as they were determined to be too vile to continue. It is worth it for Athena, pure tv gold.