We’ve put together some suggestions if you’re stuck though.
Here’s the best rulers to pick at the start of CK3, in both 867 and 1066.
This can be inherited by heirs as well.

High Chieftess Daurama of Kano
Daurama is a brilliant starter for something a little different.
Jarl Dyre ‘the Stranger’ of Konugarr
This guy’s a bit down on his luck.
However, he’s got a lot going for him.

King Sancho II ‘the Strong’ of Castille
Sancho is a strong ruler.
The best bit though?
Thakur Vijayabahu is a great choice for 1066 thanks to his ability for quick expansion and strong lineage.

Be careful though - the initial war is far from a gimme.
Those are our picks for the best starting rulers in Crusader Kings 3!