Topic: Is uploading PNGs or JPEGs better?

More specifically, if an image has the same resolution on both a jpeg and png copy, but the png copy has a bigger filesize, is it still worth uploading the png? or should you only upload the jpeg copy
Also asking because I'm uploading from one artist who has everything on their site, BUT it's not actually PNGs, they're webp files when downloading them, making them actually a png bumps up the file size to more than the jpeg copy, so should I just not bother and post the jpeg version and call it a day? :P

To the question in the title, It Depends™
If the jpeg has much better quality (at least 2x resolution), upload it, otherwise upload the png. (Read more here)
if they are the same quality, and have the same compression artifacts, upload the jpeg since the png is just a converted jpeg
File size is an irrelevant factor to quality

thatlewddude said:
More specifically, if an image has the same resolution on both a jpeg and png copy, but the png copy has a bigger filesize, is it still worth uploading the png? or should you only upload the jpeg copy

In general, PNGs are preferred over JPG/JPEGs due to the former having lossless compression while the latter having lossy compression.
When comparing between PNGs and JPGs, the JPGs should have visible compression artifacts around the edges of lines while the PNGs lack such blemishes.
Thus, original PNGs should NOT have any artifacts due to the compression method mentioned. A JPG converted into a PNG will still retain these artifacts.

In terms of uploading, we want what the artist gives in its original format and the highest quality, so we will need to know what website you are getting the images from.
We do NOT want people artificially enhancing images by disguising a JPG as a PNG or upscaling/inflating an image to have a higher file size. That will get you into trouble.

Also asking because I'm uploading from one artist who has everything on their site, BUT it's not actually PNGs, they're webp files when downloading them, making them actually a png bumps up the file size to more than the jpeg copy, so should I just not bother and post the jpeg version and call it a day? :P

What do you mean by "making them actually a png"? Are you converting them by yourself?
If so, don't do that. You are not making the image better and trying to upload that will only get you into trouble like I mentioned above.

BTW: For WebP's, it gets 'interesting'.

Opened up a 100% quality JPEG and a highly-compress WebP with nearly same perceptible quality when zoomed in (the artifacts were different). However, the histograms tell a very different story. Some are quite extreme with banding on the higher compression ratios.

I found a good SFW image to test with: post #5813512 You can see the color curve move around quite a bit. Open that in IrfranView, save a copy to same folder as WebP, and then press shift-H after loading them both side-by-side. Even at the default aggression, it's obvious.