i7 10700k (8cores 3.8ghz, easily overclocked to 4.5 without heat or performance issues)
32GB DDR4 4000mhz
Previously and during play with Stellaris, a GTX 1060 but that is in a second system now. Upgrading right now remains a pain.

Both my SSD's are Samsung 2TB, the game was installed on the primary SSD along with the OS (Windows10 Eeew) The other is my media and games library for GoG.
All built around a very slick ASrock mobo.
As for game settings, as much as I hate playing on small galaxies, I am forced to do so, often with maybe 7 AI tops. 0.5 habitable planets.
The thing is, I (usually) rebuild often, all custom rigs and I can safely say that I have had consistent major performance issues with Stellaris since the 2.0 update, regardless of the rig I build. I will say I don't often use AMD CPU's even given Intels recent slump in performance and innovation. But I've tried AMD GPUS, Nvidia, it just doesn't matter.
I appreciate that there seems to be plenty of people who don't get serious slowdown. But for me, and especially on the current rig, ticks become so slow, that a single year of game time, can take upwards of 10 to 20mins. That's just not sustainable or enjoyable and with each DLC, each patch, that adds more bloat, the performance continues to tank.
I recognise that some people are going to be rolling their eyes at what I'm saying, it's a constant refrain of mine on this board when I come around, but I wouldn't talk about it, if it wasn't an issue.