I'm not using upscalers, as their result is visible and annoying. I use primary txt2img generation at 960x540 and then img2img it with the same parameters to 1920x1080. I have experimented with all the upscalers I have in automatic1111 and none of them look naturally.
You can see the same effect on kitsuneyoukai's comic pages. He draws them on small resolution and then uses the upscalers. It doesn't look good.
I'm not using upscalers, as their result is visible and annoying. I use primary txt2img generation a