Two different vehicles...The Tacoma as a pick up is built beefier and as such designed to haul with the usual north/south drive train orientation. The Highlander is unibody and the engine is transverse (FWD) and if AWD has a small transfer case and smaller rear differential. So even though it can tow, it's structurally not as stout to haul as much as the Tacoma. So both can do what you need in winter, but what do you want or need most of the year when there's no snow?  

If your primary purpose is towing I would definitely go with the Tacoma, but if you are wanting to drive the car regularly or carry a lot of people, while also being to tow 2500lbs, you should get the Highlander. It just depends on what your priorities are.

Whatever fits your function, the Tacoma is a truck and the Highlander is a midsize crossover

I would go with the Tacoma myself.

There's a model that kind of splits the difference between the Tacoma and the Highlander - the 4Runner has a truck-like frame and toughness, more car-like  comfort and handling than the Tacoma.

Both will easily meet your towing needs without issue, chose whichever vehicle you otherwise prefer.  There is no reason to think you need to maximize towing capacity for 2500lbs.  6400 capacity isn't better than 3500 capacity for towing 2500.

To my knowledge both are great vehicles. However if I was wanting a tacoma and looking for an SUV. I’d consider the 4Runner too along with highlander. The Highlander will ride smoother and seem more luxurious and get better MPG. If you haul more people around the highlander has a 3 row. If you tow often tacoma. If not and you need more seats Highlander.  

For occasional general light towing, the Highlander seems like a good option on paper.  But I would strongly suggest the Tacoma, no question.  And not just because it is just an all around better tow rig.

For snowmobiles, you also have to take into account where you're going and what you're doing.  Bad roads, dirt roads, unplowed roads, snowplow chunks, and so on.  The Highlander doesn't have the ground clearance or the appropriate tire options to tow snow machines. 

At any snowmobile snow park, you will see mostly half- and 3/4-ton Chevys, Fords, and Rams.  Occasional Suburban/Tahoe, occasional Tundra. And occasionally a Tacoma pulling a single-place trailer.  And I guarantee that the majority of them will be riding on BFG KO2's.  That's just the set-up that works.

In 20 years of snowmobiling I don't think I have ever seen a Highlander tow rig.  1 or 2 Subaru Outbacks, but no Highlanders.