Whichever matches how you actually work. JPEG is simplest and the camera does the processing for you. RAW keeps more information for recovering highlights, adjusting white balance and handling bright snow against dark wildlife, at the cost of storage and the need for software. RAW plus JPEG gives you both and uses the most space.
There's a lot of pressure on beginners to shoot RAW, and it's misplaced. A technically superior RAW file is worth nothing if you don't know how to process or store it, and it will fill your cards twice as fast while you learn.
If you edit photographs already, RAW is the better choice on this trip specifically, because the snow-and-dark-wildlife combination is exactly where the extra latitude pays.
If you don't edit, shoot JPEG and spend the attention on exposure compensation instead. That single skill will improve your snow photographs more than the file format will.