I personally use 1280x and 1650x.
1920x is not ideal as I was told 3 years ago when discussing Overwatch (CSGO spectator anticheat system) that the higher resolution the more inputs your mouse will send on screen thus it should be easier to detect if someone is using artificial aim.
My cheat is designed to fool anyone spectating but the higher res you play on the harder it gets to fool the observer.
You can request a new copy on the forum if you want 1280x.