Amsterdam has:
- The largest internet exchange in the world, which means very cheap and high quality colo
- Several large universities with CS departments in the vicinity should you need team members
- Excellent quality of life
- People speak several languages, including English
- A great startup scene
- Tax breaks on innovative (software) products
Downsides: not cheap and hard to get a working permit if you're from outside the EU. Don't go there if you get offended by a very liberal value system.