I haven't watched any of the "big" series -

[Bemyclementine]

Like Breaking bad etc

Which would you recommend?

The Fall.

Yes! Brilliant series.

Although you’ll never get the hots for Jamie Dornan ever again after watching it. <shudders>

Breaking Bad for me, definitely. Should have stopped at the end of season 4 though.
Better call Saul.
The last Kingdom - fantastic, based on the Hugh Cornwell novels.
Unorthodox. Had me in tears several times.
Currently enjoying Only Murders in the Building - light hearted, Steve Martin and Manhatten as a backdrop, what's not to like?
I personally couldn't get into The Sopranos. Wanted to like The Wire but couldn't cope with the mumbling!

The Wire, The Shield, Sons of Anarchy.

If you really want to go back in time see if you can track down Tinker Tailor Soldier Spy. The Alec Guinness one, not the 2011 film (although that’s also good).

If you haven’t seen

I May Destroy You

then you won’t know what 21st century TV can achieve.

And if you want deep emotion you need all the seasons of

My Brilliant Friend

Agree with most posts above - but bear in mind everything you watch will merely be preparation for

Succession.

Orange is the new black

The X-Files
ER
Homeland

-The Walking Dead. Last series is a bit meh but there are a 11 in total and the early stuff are great!!
-The Following
-Game of Thrones

Yes!

Dexter
The Walking Dead (provided you like zombies!)
Stranger Things
Z Nation (again a zombie one, but a lighter hearted version than TWD)
The Good Place
Killing Eve
Shetland

True detective series 1 was probably the best thing I have ever watched on tv.

Breaking bad - the best tv series I have ever watched
Game of Thrones
Killing Eve
Queen of the South - so underated and my second favourite series I have ever watched!
Homeland

Reading these lists I’ve realised I haven’t either

The one I have which was excellent is Mad Men

I found the Sopranos incomprehensible because of the accents

I really liked:

The Good Place
Veronica Mars
Jane the Virgin
Desperate Housewives
Private Practice (but weirdly couldn't get into Grey's anatomy)
The Good Wife

I'd go upmarket and watch Succession. I've not watched any of those mainstream shows....

Yes Succession is brilliant

The Bridge
Spooks
Happy Valley
Broadchurch
Line of Duty
Money Heist (my absolute favourite of all time- ignore meh title)
Wisting

I'm realising I haven't seen many of the big American Netflix etc series.

Just stormed through all of Dexter, can be found on Paramount at the mo.

i didn’t think it would be my thing but really couldn’t get enough of it from the off. A surprise round every corner in every single episode !

West Wing
Breaking Bad then Better Call Saul
Mad Men
Suits

It's very, very slow.

Billions (Damien Lewis)
Power
Sons of Anarchy

@FuckabethFuckor I really fancied him in it. It made me question my life values 😂

I fancied the fit cop Stella sleeps with in the first episode. I was very upset when his story arc ended (trying not to give away spoilers there).

Did you notice — it took me two watches to pick up on this — that pretty much every single male character in that show violates boundaries in some way. It was brilliantly done, so insidious.

Following lots of recommendations above:
The Sopranos
... and if you like that maybe the Wire, with subtitles being useful
Band of Brothers (if you fancy a drama about the realities of war)
Mad Men

These programmes score highly because they reach a conclusion. Not an ending where everything is all neatly resolved and tied up but they avoid the fate of many long running series which just can't find an end point and continue on losing their way and what originally made watching them worthwhile.

If Breaking Bad is the best tv show ever, and it is in my opinion (just couldn’t get into The Sopranos) then Better Call Saul is the second. It is a slow burn but by the end the tension is ramped right up. And something happens in the last season that made me look at the events of Breaking Bad completely differently.

Make sure you watch BB first. Most of the events in BCS happened well before BB but you need to see it first.

Think everything on my list has already been mentioned, but that shows how good they are I guess!

Grey's anatomy
Mad Men
House
Suits