[noname219]

Good call on Rhubarb. A lot of post-rock bands seem to fit the cathartic label too. Also, classical and modern film composers. As well as a bunch of ambient and progressive artists.

Here are some, gonna use links, not to overload the page :

Anathema - Hindsight
BT - Good Morning Kaia
Clint Mansell - Together We Will Live Forever (the whole soundtrack fits the description)
The Evpatoria Report - Dipole Experiment
Girls - Vomit
God Is an Astronaut - All Is Violent, All Is Bright
Godspeed You! Black Emperor - Motherfucker=Redeemer (Part Two)
John Murphy - In the House - In a Heartbeat
Kayo Dot - The Manifold Curiosity (in a different way)
Oceansize - The Frame
Portishead - Roads
Pure Reason Revolution - Bullits Dominae
Sigur Ros - Popplagio
Ulver - The Future Sound of Music

If I was to chose a top 5, I would pick those bolded.