NetHack was my very first Roguelike and I ascended for the first time in 2009. I have since gone on to play many other Roguelikes, including DCSS.
I managed to win DCSS with all species, backgrounds, and gods over a period of a few years. Since then I’ve mostly lost interest in playing, and have returned to NetHack which to me feels as cozy as an old pair of slippers.
With what I know of both NetHack and DCSS, I prefer NetHack these days. DCSS is very interesting, tactically, in the early game but as you go along it becomes more and more about “keep doing the thing this character is good at” and the tactical variety vanishes. NetHack isn’t a whole lot better in that regard, but NetHack isn’t purely about tactics anyway, so it matters a lot less.
The Roguelike I most enjoy for its tactical prowess is Shattered Pixel Dungeon, which is far more interesting on that level. It has much more customizable characters, with talent points and a nifty scroll of upgrade system for weapons, armour, throwing weapons, wands, and rings (a system it borrowed from the game Brogue, a reimagining of the original Rogue). This character customization system is combined with a more interactive dungeon (full of traps you can trigger against monsters, spreadable water/grass/fire/poisonous gases) and a highly in-depth alchemy system that lets you recycle “junk” items into extremely useful and powerful resources.
On top of all that, SPD features a challenge difficulty system with up to 9 challenges that can be toggled independently and in combination, with the full 9 challenges presenting a worthy foe even for seasoned veterans of the game.