Nethack is a turn-based roguelike. Diablo is an action-oriented dungeon crawl (the original at least; I never played Diablo 2 or 3). To me they don't "feel" the same enough to compare which one is better.
I'm a fan of roguelikes too, by the way. If you want to try a somewhat different roguelike for Linux, I recommend Teleglitch (commercial, scifi, quirky graphics, real-time, brutal gameplay).
I respect your purism! But do try Duskers, regardless of classification. It's a cool game and shares some traits with roguelikes: autogenerated world, stuff to find and equip, permadeath, and high difficulty as the game progresses (though it's deceptively easy when starting).
Teleglitch is punishingly difficult from the start, and pretty fast paced too, so maybe give that one a pass.
I mean, in philosophy, Diablo and Moria were related. The initial plan was to release Diablo as a modern Moria, and yes, turn based, but they switched into real time and they simplified the game for the more casual generation.
If any, Flare RPG has anything the first Diablo offers with a longish campaign and a good set of skills.
I know, but I can't stop comparing it to Moria/Angband.
I know the timing changes everything (and Nethack is more like a text adventure lore made into a top-down RPG), but the environment and tasks ingame aren't so that different both in Diablo and Moria.
Nethack is a turn-based roguelike. Diablo is an action-oriented dungeon crawl (the original at least; I never played Diablo 2 or 3). To me they don't "feel" the same enough to compare which one is better.
I'm a fan of roguelikes too, by the way. If you want to try a somewhat different roguelike for Linux, I recommend Teleglitch (commercial, scifi, quirky graphics, real-time, brutal gameplay).
edit: and Duskers! How could I forget Duskers! For a really different scifi roguelike: http://duskers.misfits-attic.com/