In a mostly snowy world (snow deserts, snow jungles, etc) with a few underground cities built with magitek, most popular vehicles are rovers/gliders (think speeder bike from Star Wars). Would there be any advantage to wheel based vehicles?
There are two primary reasons why wheel based vehicles might have advantages in certain instances over hovertech; energy and failsafes. Energy is the most broadly applicable, so we'll deal with it first.
Wheels are still around because they cost less energy to operate.
Wheels are designed to do one thing; make it as easy as possible to move something in a direction that's perpendicular to gravity. In point of fact, wheels wouldn't work very well without gravity. It pulls the wheel down to the road, putting tension on the system that translates to friction. The rubber tyres on most wheels today are there specifically to make the friction between the wheel and the road higher than the friction between the hub and the axle. As such, you apply lateral force to the object on wheels, and it's the hub that moves (rotation), not the tyre (sliding).
The practical upshot of this is that you can move things along the ground with a wheel using FAR less energy than you can move things through the air, because you're constantly fighting gravity as well. That means that unless you have an anti-gravity tech or an atmospheric pressure trick (like the shape of a plane's wing) you are going to be using a LOT more energy to move things along the ground. This is why we don't all have hovercraft or hoverboards or the like right now; technically they're possible, but the power requirements and the cost of building such sophisticated systems is much higher than just putting wheels on things.
This of course leads into the second reason, which is even more important to consider for combat purposes;
Being suspended above the ground is not a 'fail-safe' position
The reason why we have air traffic controllers but feel at ease with automated ground traffic control (like traffic lights, give way and stop signs, etc.) is that if a car fails, it's already on the ground. That's not to say that it's not still dangerous, especially travelling at speed; but if an airplane fails for any reason, it fails badly (unless it's still on the ground). Your hovertech is going to be subject to the same problem insofar as it only works while the power is on. The second the power fails, so does the movement capability of the vehicle. Falling the 50cms or so to the ground probably won't cause too much of a problem, but you certainly won't be able to push it to the nearest garage to fix it.
If these are combat vehicles (I'm making an assumption here based on the mention of Star Wars) then this is NEVER an ideal scenario. All ground based combat vehicles are likely to (at the very least) have wheel options as a backup, because without mobility in a battle, you're a large stationary target and that's very bad. But even without combat conditions, you're still not going to want that kind of situation for your vehicles, because of the other dangerous thing that most definitely IS in your world;
Most tech doesn't play nicely in the cold, and it's entirely possible that between snow getting blown around by the downward jets allowing the vehicle to hover, water being melted from ice by exhausts only to refreeze on parts of the vehicle, etc. that you're going to have vehicle failures. People also don't fare well in extreme cold, so you'd need emergency gear available to you and you'd also need some way of getting the vehicle somewhere warm so that you can fix it in what's called a 'shirtsleeves environment'; somewhere comfortable to work in without wearing bulky survival suits. Again, just being able to tow it (wheels) will be a great boost in the ability to get the vehicle and crew somewhere practical should the engine fail for any reason.
Hope for the best, plan for the worst
Wheels are great for energy efficiency, meaning that your vehicles will go further with less energy, allowing you to divert excess energy to other priorities. Also, they can still function in situations where energy reserves are quite low, whereas your hovertech won't.
Additionally, wheels are just plain safer because they're fail-safe tech, not fail-badly tech. Also, in a worst case scenario, you can get in your survival suit and just push the thing if you really had to. You can't do that with skimmers and the like.
As for proof; well we're still working with internal combustion cars that are becoming more and more efficient with fuel to get people where they have to go faster and faster (and more safely). Hover and air cars aren't in our future and are not being proposed as replacements for the car because we already have the most effective, energy efficient technology under us every day.
Err... Have you ever tried to drive in snow? Wheels don't work too well, even with just a few inches/cm over a paved road surface.
Absent handwavium-powered antigravity, hovercraft won't work all that well, either. They work by blowing high-pressure air out the bottom. In snow, that air is going to produce a horizontal blizzard. If the snow is soft, it just might create a hole deep enough to get your hovercraft stuck.
No, the way to have powered vehicles in a snow-covered world is just the way we do it in the snowy areas of Earth: tracked vehicles like snowmobiles and snowcats https://en.wikipedia.org/wiki/Snowcat
Hmmm. Not that I can think of.
Hovering vehicles wouldn't have the risk of getting stuck in snow or having to deal with not having traction. Heck, if you design the rovers with smooth undersides, you could use them as sleds in emergencies. It's a total upgrade as far as I can see.
If you want some more diversity, I would recommend thinking about carrying limits. If the rovers are incapable of carrying, say, two dead moose, it might make sense to have a bobsled or snowmobile to haul cargo.
Or maybe they are limited in fuel, so long distances are impossible unless fresh rovers or fuel depots are laid out beforehand. If that is the case, wheeled or on-sleds caravans carry rovers with them in the event they need to make emergency runs or defend themselves.