Easy...680 and 676 weren't out, only the 659.
Personally, I like the sleek look of the 680. Though the other ones may have a better tactile feel. Harmony service has been outstanding to boot.
I like the 880 but not sure how much I'd get out of the icons and charger. I used to have the 768 which was WAY cool since you could program it w/ XML. But the button layout wasn't ideal at all for PVRs. An 880 w/ XML would be the best of both worlds.
For great prices and support, try bluedo.com and surfremotecontrol.com.
