What is a good word to describe 'exceptional positive' research work?

You could say X has the potential for seminal research.

seminal
4. highly original and influencing the development of future events: a seminal artist; seminal ideas.

If you don't want to make such an extreme prediction, I would go with Rimmer's suggestion of groundbreaking.

What about groundbreaking?

Innovative; new, different; doing something that has never been done before.

How about pioneering? This often seems to be used for breakthrough medical research in particular.

There's also cutting-edge, bleeding-edge and the like, which are commonly used in technical fields.