Genndy Tartakovsky’s 2003 Clone Wars series.
It is mad, fun, highly stylized, and is canon (before Disney said it wasn’t in 2012, which doesn’t mean much to me). It also feels very Star Wars, despite not being anything like it in that universe before. It is not for all tastes, but that is okay too.
I think Tartakovsky did an awesome job with the series, and is a bit of shame we had to wait until the recent Star Wars: Visions anthology series to see anything this different again.
I hadn’t thought of the 03 Clone Wars as underrated, but now that you mention it, I agree. It doesn’t get nearly enough recognition from fans these days. It really is something special.