Which game would it be ?

Tales of Maj'Eyal. That's all the Roguelike you really need. Playing through the various combinations would take years.

I did not play Tales of Maj'Eyal but I just love Darkest Dungeon so my vote goes here.

Sunless Sea, hands down.

Tales of Maj'Eyal

The newly released ADOM or ToME.

I'll admit I'm not really sure what an actual roguelike is, but if it's taken broad enough to be anything with permadeath, procedural generation and an emphasis on exploration, then without a doubt it would be a fight to the death between
FTL and
Don't Starve.

Darkwood definitely deserves a mention as well, though there permadeath is only if you choose the two highest difficulties. It's a deeply disturbing and unsettling game though, but it's also hands down the best I've seen a game at telling a rich story using only subtle elements. You really have to pay attention to notice all the details that gradually flesh out what happened in the world, and in some cases what is still going to happen.

Now that would be Dungeon Crawl Stone Soup
Followed closely by
DoomRL cause Doom+Demons+Shotgun+RL

ToME 4 for me as well, although SOTS: The Pit is pretty great too.

Nethack or Dwarf Fortress.

I've asked this before

Dungeonmans

It pretty much has the most going on

A lot of these games are so bloody similar with just one or two tweaks

I just uninstalled Mana Spark thinking to myself that, although good ,
It's just Moonlighter without the added feature of going home and selling found loot in a shop
so plan on getting Moonlighter to complete first before attempting Spark again.

I'm a little vague on the term "roguelike".

I only just recently figured out ARPG and Metroidvania, so bare with me. :P

Roguelike, bearing in some term to Rogue, a turn based top down dungeon crawler known for complexity, with permanant death and one singular goal over many levels. The content is randomly generated and death awaits around any corner. [url=https://en.wikipedia.org/wiki/Rogue_(video_game]https://en.wikipedia.org/wiki/Rogue_(video_game[/url])

Diablo I is a roguelike, Nethack is a roguelike, FTL is a type of roguelike.

Diablo is turn based? Since when? :P

There's many qualifiers to a roguelike, of which Diablo matches most criteria. Massive dungeon, equipment is random, monsters are grouped by level, and so on.