Rockstar - Working on GTA VI. These guys always push the consoles to the limit. Huge man power. In terms of tech and visuals and always near or at the top of the game.
NaughtyDog - Supposedly working on TLOU Remake (rumor) and a new IP. These guys have released some of the best looking games in each respective generation. Some of the best animation, rigging and mo-cap I've seen in in-game models and cut-scenes.
Santa Monica Studios - GoW Ragnarok (Crossgen), working on on new IP, no announcement yet - so most likely due in a few years next gen only. Similar to ND.
Ninja Theory - Hellblade looked fantastic, as is arguably on the best looking games on last generation consoles. HB2 looks crazy good thus far.
CD Project Red - We already had a taste of 'next gen' on PC with Cyberpunk 2077. Visuals and tech the past 2 generations have been up there with the best - though Cyberpunk was quite poor in terms of polish upon release.
Playground Games - Worked on Forza Motorsport series - some of the best looking visuals in racing games. Working on Fable.
The Coalition - Worked on Gears 5. And with Epic to get UE5 demo optimised for Series consoles. Likely working on Gears 6.
I'd put Quantic Dream down though their next game (Star Wars Eclipse) is a cross gen/cross platform game so.. maybe not.
Great list, I'll add
Kojima Productions. Although it's departure from Konami has definetly a setback every new Kojima games has almost always raised the bar expecially in terms of realism and character animation.
Id Software. Altough thier focus isn't realism but rather world detail with an high level of performance. Doom Eternal has been one of the most impressive technical achievements of this generation and I can't wait to see thier next game tailored for next gen hardware.