Check out our Forum Rules. Lets keep this forum an enjoyable place to visit.
I think my single favorite is the Norwegian Chamber Orchestra, because how many orchestras do this?
Other favorites include...
The London Firebird Orchestra:
The New Century Chamber Orchestra:
But there are many more outstanding chamber orchestras out there. Look into the Orpheus Chamber Orchestra, the Chamber Orchestra of Europe, the Concertgebouw Chamber Orchestra, the Mito Chamber Orchestra, the New York Classical Players... and I'm probably still missing several that I love.