I am planning to do the Kangchenjunga base camp trek (in Nepal) in the coming months. I read that a tent is a must for this trek as it is not a tea house trek. I am thinking of buying a tent for myself but my dilemma is do I choose an all season tent or 3 season? Which will work best (in regard to the weather condition in high altitude of Nepal) or what kind of tent is suitable for the trek keeping in mind that I may also need it in the future for other trails?
If there's a solid chance you're going to encounter snow or heavy wind during the trek ( and I'm guessing there is with those elevations ) or the future treks you plan to use the tent with, it's unlikely that a 3 season tent is going to be enough for you. 3 season is a category meant for tents that aren't intended to stand up to wind and snow.
Though, if you feel strongly that a 4 season tent is overkill, there's a category called extended / 3+ season. As the name in implies, it's falls in between 3 season and 4 season. Paraphrased from http://www.rei.com/learn/expert-advice/backpacking-tent.html :
Extended season tents typically include 1 or 2 more poles and fewer mesh panels than pure 3-season models. This makes them sturdier and warmer than their 3-season cousins. Heavier, too, but not by huge amounts.