Even their first original show Oz (1997) [1] was good. It was clearly experimental and low budget (it's set almost entirely inside a prison so needs very few sets, props, costumes, etc.), but designed around that limitation to focus on the writing and characters. Netflix tried a similar strategy with one of their first original series, Orange Is The New Black.

[1] https://en.wikipedia.org/wiki/Oz_(TV_series)