Personally I won't touch Altec Lensing and Logitech.
I own Altec Lensing ACS48 before. Bought it after reading rave reviews, listen to it and learn my lession - never believe the reviews!!! Later switch to MicroWork and happy with the sound. Recently just upgrade my MicroWork to MegaWord 510D.
Logitech, I had a chance listen to Z680, found it is more suitable for DVD video playing or gaming, but not music listening. But that's my personal experience.
Didn't have a chance listen to Crossfire and Aego2, thus no comment.
Personal recommendation, I would suggest for Klipsch Permedia series and CSW MegaWork series.
P/S:- I done a small test, by switching the satelite of MicroWork and MegaWork, subwoofer remain MegaWork unit, found MicroWork satelite are more forwarding, MegaWork satelite are much better control.