More Intense:
* Astonishing: Causing great surprise or wonder.
* Awe-inspiring: Inspiring a feeling of reverence and wonder.
* Extraordinary: Uncommon, exceptional, and remarkable.
* Phenomenal: Remarkable, extraordinary, and impressive.
* Spectacular: Strikingly beautiful or impressive.
* Stunning: Extremely beautiful or impressive.
* Unbelievable: So extraordinary that it seems impossible to believe.
More Specific:
* Brilliant: Extremely clever or talented.
* Magnificent: Very beautiful, impressive, or grand.
* Marvelous: Wonderful, astonishing, or amazing.
* Prodigious: Extremely large or impressive in size or scope.
* Remarkable: Worthy of attention or notice.
* Sublime: Inspiring awe and wonder.
* Tremendous: Extremely large or great.
Informal/Colloquial:
* Amazing: Causing surprise or wonder.
* Awesome: Impressively great or powerful.
* Cool: Excellent or impressive.
* Fantastic: Extremely good or impressive.
* Out of this world: Extremely good or impressive.
* Rad: Very good or cool.
* Sweet: Excellent or impressive.
The best word to use depends on the context and the specific shade of meaning you want to convey.