I'd stick to Canon. Not because they're the best or they fit your needs--that's a "Ford vs. Chevy" debate. It's because you've already got a Canon so if you upgrade your body, there's a chance your existing batteries will work and your existing lens might work (again, depending upon what you buy). Plus you're used to the Canon menu system (even though you're inexperienced). I say all this as a long-time Nikon user. Everyone has their favorite. Frankly, the camera body isn't going to mean that much (especially if you're inexperienced with photography). Your lens and your preparation will matter more than the camera body.
In an ideal world you'd buy mirrorless. They're smaller and lighter (and for multi-day hikes that's critical). You ideally want to take one lens. Changing lens in the outdoors is something you want to do as little as possible (to avoid getting dust in the body). Do bring extra batteries. And if you buy mirrorless, buy extra extra batteries--they run through juice like crazy.
If you're going to be shooting sunrises and sunsets or wild animals in a lot of darkness (say...a poorly lit forest), you'll need a tripod. If you get a good one it can double as an okay hiking stick. But let's assume you're not shooting in low light.
In that case, ideally you'll look for what is called a "super zoom" lens. It's a lens that will shoot at around 30mm (ideal for landscape) and as far out as 200mm or even 300mm (important for wildlife). Important points--sharpness of detail with such lens is going to go down a lot at the extremes. And all zooms are not as sharp as a good prime lens. But if you invest in a super zoom lens you'll keep it on your camera and won't need to swap lens. A super zoom will probably weigh a lot but that's better than carrying two lens and having to swap them in and out.
