[user104658]

Flashforward was a great concept that was really poorly executed - I can see why it didn't last to be honest.

I'd give a shout to "Heroes" - it's not well remembered because it went totally off the rails in later seasons and was cancelled, but the first few seasons were great and season 1 was actually really brilliant. A shame the ball was fumbled. It was largely because of the 2006 writer's strikes. In hindsight also an absolutely top-tier cast, a lot of the people who weren't particularly well known at the time have gone on to be much bigger stars e.g. Milo Ventimiglia, Zachary Quinto, Hayden Panettiere.