Hmm, top 10 Haken songs you say...
In no particular order...
Eternal Rain*, Insomnia*, Celestial Elixir, Cockroach King, Falling Back to Earth, Pareidolia, Crystallised, 1985, The Endless Knot, The Architect
With both Eternal Rain and Insomnia, it was hard to pick one song from the respective albums, though I believe both deserve to be recognized aside from Celestial Elixir which is an easy choice. There are 3-4 tracks from both the first two albums that I could have chosen in place of Eternal Rain or Insomnia.