Sort of depends what she wants it for.
I like a mini chopper, which are super compact and can make quick work of dicing onions, making pestos, even making hummus. But you won't get something entirely smooth and pureed. For example if I put chunks of onion in a mini chopper it will be very finely cut, if I put it in a nutribullet it will be entirely pureed. And you are restricted to fairly low quantity.
I also like an immersion stick blender, I had one at uni and it used it alot for soups or if I wanted a smooth curry base. However, as with mini chopper it's almost impossible to get something completely smooth, though for me it was good enough. It is really handy ton use it with hot liquids, and it's small to store and easy to wash up.
Nutribullets (or similar) are amazing for creating a completely smooth liquid, and I find mine handy for much more than just smoothies. But the big downside is having to wait for things to cool before blending. The capacity is fairly decent, but not that big. I wouldn't be without mine, but I also find it the least flexible.
I've never had a 'proper' blender so can't really comment, but blending very smooth even while hot is a major bonus above the others above (all of which I currently own) but I think you can struggle with small quantities, so things like pesto wont work.