Brogue is very traditional and very thoughtfully designed. It's the author's idea of what Rogue might look like today if development had continued.

https://sites.google.com/site/broguegame/

It's my favourite Roguelike because it's the genre distilled to its essence. Also the short bits of flavour text are very well written.

Desktop Dungeons is an excellent one. Gameplay is divided into levels which are designed to be short, and there is a puzzle mode which is tricky but very rewarding. The race/class system is also quite good. Different builds are good on different missions. http://www.desktopdungeons.net/

Dungeon Crawl Stone Soup[1] was how I was introduced to roguelikes. Try starting out playing as a troll monk (trolls can eat raw flesh and won't starve as easily, and they have claws for unarmed combat).

[1] https://crawl.develz.org/

ADOM (Ancient Domains of Mystery) is a favorite of mine. I prefer the original CLI version to the Steam version (especially since the original is free). Dwarf Fortress is also very satisfying though it does have a higher learning curve.

I have been playing Nethack (and Slash'EM, a variant) on and off since the 1990s. It's one of the early off-shoots of the original game, Rogue.

I compiled it from source using DJGPP for MS-DOS (which is a GCC port for 32-bit DOS executables) and added my own random humorous messages to various situations in the game. I also made some minor modifications to the game mechanics to fix things that I personally found annoying.

Compiling was in itself a fun endeavor - it took a couple hours to recompile from scratch, as I remember, and of course there was always a surprise or two along the way - invariably due to my own errors.

Both Nethack and Slash'EM are still actively developed, and there are graphical tile interfaces available now, too. The learning curve is a little steep due to the large number of keyboard commands. That seems to be a common feature of many roguelike interfaces.

If you want to check them out, be aware that the console version usually defaults to the safest and most boring set of options - no color or graphics chars - so if you play that one, you might want to set those options first. Or go with one of the many graphical tile versions.

Also, beware: this was more of time sink for me than WoW ever was. YMMV.

This thread just reminded me of Cogmind. It's Windows only and I had forgotten about it when I moved to Linux but it's working with Wine so far. It's a really good one. Early access and not free ($24 min) but it's very stable and easily worth the price.

Brogue is very similar in spirit to the original. It was excellent game balancing and isn't overly complicated. Compared to many other modern RLs, this one is very approachable and allows one to make progress early.

Cataclysm: Dark Days Ahead is my favorite game of all time.