My favorites are mysteries or police procedurals, and most of them are British (the first 6 below). I agree Better Call Saul is brilliant, though I lean more toward Fargo as a crime drama. Saul is in a category of its own.

In no particular order:
Vera
Shetland
Line of Duty
Endeavour
Broadchurch
Grantchester
Jack Irish
Top of the Lake
Trapped
The Brokenwood Mysteries