Formal:
* Exemplary
* Unparalleled
* Unsurpassed
* Benchmark
* Gold Standard
* Peak Performance
* Summit of Excellence
* Apex of Quality
* Pinnacle of Achievement
* Top Tier
Informal:
* Top Notch
* First Rate
* Best in Class
* World-Class
* Outstanding
* Superb
* Exceptional
* A cut above
* Beyond compare
More specific options:
* State-of-the-art (technology)
* Best Practices (processes or methods)
* Award-winning (achievements)
* Premium (quality)
* Luxury (experience)
The best choice will depend on the specific situation and the intended tone.