RAW!
You will often hear experienced photographers talk about the JPG file format as a bad thing and RAW as the way to go. But I think there is a nuance to this: horses for courses.
It is true that JPGs are more “locked in” in terms of what you can do in post processing. Some have described RAW as the ingredients in a meal, and the JPG as the cooked food, and the comparison is not that bad. The RAW format gives more headroom in recovering details from bright highlights and dark shadows and you can also do much more editing if colors and white balance etc than JPG allows. And the quality of the JPG file is subject to the in camera processing of the image and hence the quality of the software in the camera.
But it comes with a price, and the price is disk space or storage space. RAW files store a lot more information per pixel than a JPG does, and this is why JPG files are so popular on the web where fast load times are a key factor. The resolution of a RAW image and a JPG image is the same, but the amount of information stored per pixel in the RAW format is much more than the JPG. Also, the JPG file will be subject to compression where a lot of information can also be lost.
So to say that RAW is good and JPG is bad is to simplified. Sometimes you just don’t need all the flexibility that a RAW file offers, and if you shoot a lot of images the amount of space saved can be significant. Also, if you plan to use the images as JPGs because they need to be small, shooting in JPG directly saves you the conversion from RAW to JPG in post processing. So you may save both time and storage.
I often shoot JPG when I have a very controlled environment like a studio with flashes in a tethered setup where the image is loaded directly into Lightroom for viewing large scale. Here I can quickly see if the colors and metering is spot on or not and adjust accordingly. Where I need the RAW file flexibility is when more variables are not under my control. Like when shooting in low light or shooting into the sun. Here I prefer the headroom in post processing that RAW files give.