Thanks for comment!
1 - well, the upscale methods isn't mine, just for clear. My observation is
a) animevideov3 - the fastest method (couple of times than the others) and usually the best for anime video, but not soo good for images
b) x4plus - meh... its not so good for anything. Sometimes the best for images but its like 1 to 20.
c) x4plus-anime - the best for 2d images, like anime or fan art from deviant art and similar. I use it for anime video, but it takes sooo long and the result not so good, i prefer use animevideov3
2 - definitely x4plus-anime
3 - Auto mode takes already selected mode, so you have to change it before clicking auto mode button. I suggest to choice animevideov3 mode and x2 scale. This way makes you the fastest and the most quality result.
Remember that, this upscale methods is for 2d. For more information look at https://github.com/xinntao/Real-ESRGAN