[spoilers] what is the best series of spooks

[Forever Secret]

I think Series 2 and 4 are my favourite series. Loved Tom in Series 2 but loved Adam just as much during Series 4 I thought Series 2 had some of the best writting in Spooks as well, 2.5 remains my favourite episode of all time, there was just something about the way it was written that make me want to watch it again and again.
I liked the way that Tom's character became to fall apart, the job becoming too much for him, it's the first time we really got to see one of the team losing themselves.
I loved Series 4 because like Silktie said it was the beginning for Harry and Ruth, those small moments between them were great to watch. And I liked the addition of Zaf and Julliet as well, the stories of the week were also really good and the team began to grow as a unit, it was a more emotional ride too because of losing Fiona and just losing Danny at the end of Series 3

I'd say Series 7 and 8 were favourites too, with Lucas coming into the Series in S7 with the return of Ros and then of course Ruth coming back in Series 8, I thought S7 had the best Story arc as well with the pretty complicated Sugarhorse haha