What is the best TV series from start to finish?

[Soubriquet]

Gotta be

Buffy the Vampire Slayer
The Good Place

there are other shows I love but I think these two don’t have a single bad episode. It’s all brilliant right from the pilot to the finale

Pose
Happy Valley
Line of Duty

all perfection from start to finish.

Buffy The Vampire Slayer
Teachers
It's a Sin
The Walking Dead
Grey's Anatomy

Six Feet Under

• Brideshead Revisited, without a doubt. If you want more modern, Schitt's Creek.*

Oh my goodness this reminded me that my two all time, never to be beaten, favourites are
Brideshead Revisited and
The Jewel in the Crown

Casualty

This is Us
schitt’s creek
ghosts
Superstore
only fools and horses
band of gold
birds of a feather

I agree with quite a few of those mentioned above. I also love these, which haven't been mentioned yet:
1883
Shameless
Sanditon
Not sure if a pp was talking about Detectorists

Not quite a series but terrific. I had to really concentrate,but I keep thinking about it. UNDER THE BANNER OF HEAVEN. On ITVX I found it very unusual,

And many of the others already mentioned.

Six Feet Under

Life on Mars/Ashes to Ashes
The Wire
The Shield
Line of Duty

Happy Valley
Friends

I’m going to be contrary here - Seasons 1 & 5 of The Wire take it out of the running here.

And BB99 is my favourite tv series ever, but they should have quit before the final series.

And The Bear, another incredible series, was a lot less consistent in S2. Some episodes were mind blowing but there were a few duds, especially in the first half of the season.

Succession. Hands down the best thing I've ever seen on TV.

Extras. Watched all episodes at least ten times

Band of Brothers - I'm not usually that interested in war dramas but this was outstanding

The Bridge
Gavin and Stacey
The Handmaid's Tale

Happy Valley
Being Human
Line of Duty
The Serpent
Blackadder
Mash
Tenko
Father Ted
Fawlty Towers
The Detectorists
The Royle Family
Outnumbered
House of Cards (original - I haven't seen the US version)
Sherlock
The Office

The Middle
Last Tango in Halifax
Gavin & Stacey

Life on Mars
Ashes to Ashes
Derry Girls

Schitts Creek
The Middle
Curb your enthusiasm
Lost in Space (new)
Manifest
IT Crowd
Black Books
Father Ted
Motherland
Frasier
People Just do Nothing

Thanks for the recommendation of The West Wing - as a political junkie I am now hooked!

I mean to add Six Feet Under to my previous list.

The Wire
Line of Duty
The Good Wife
Peaky Blinders
The Sopranos
M.A.S.H.
Wednesday
The West Wing
Succession
Billions
Happy Valley
The Divorce

Very jealous you’re getting to watch it fresh! When you’ve finished watching the series there’s a podcast called West Wing Weekly which does an episode by episode breakdown and loads of cast and crew interviews.

Our Friends in the north

I’m going to add Slow Horses after just watching this. Amazing