I've seen a lot of spectacular content in YouTube but what really interests me the most is this kind of niche, Travel. You can also have a lot of clients you can collaborate with. If you produce great content, either clients will reach out to you or you will reach out to them and present them what you've got.
Another one, with travel videos, you can collaborate with, not just one, but MANY.. since travel is a broad niche. You can collaborate with technology, food, clothing, auto, and many more as long as you make it creative and unique.