For my money Tom Burke and Holliday Grainger do a fine job of providing the focal point and anchor for these superb detective whodunnits penned by Galbraith aka. JK Rowling. I suppose it's fair to say that you'll either find chemistry between Strike and Robin (the leads) or you won't.
These shows are based upon crime novels that are crammed with detail and the nuance of relationships and events, which make them a fun read - and that the series' screenplays do a great job of adapting for the screen.
Now on it's fifth novel this series only goes from strength to strength spinning fascinating and engaging tales.
As others have mentioned, locations and style also play a leading role - the result is a satisfying sense of place which complements both the action and backstory.
The Brits have a particular style to how they go about their crime dramas, an angle which places a concentration and importance on drawing out character, a recognition that the journey to the conclusion is as important as the resolution and the untangling of the 'crime' itself. We end up with an understanding of both the perpetrator and their supporting characters, and a deeper relationship with the investigators - and in this sense Strike is as much a highly successful human drama series as it is a crime and whodunnit proposition.
I'd recommend giving Strike a watch if you haven't already done so - but, although each series stands alone covering one novel (except for series one which is two novels in succession), there is a strong cumulative backstory revolving around a central group of characters, so for best results and viewing pleasure start with series one and binge from there.