The new Contend 3 is cheaper than the Defy 5, so I think you should be looking at that one, they have the same specs.

Apart form the carbon fork, other thing worth considering is the cassette. The Giant has an 11-32 and the Trek an 11-28. If you will be hitting some big hills, then you'll probably appreciate the lower gearing of the Giant, but if you ride on mostly flat terrain, then the closer spaced gearing of the Trek would be better. These are items you can change in the future, so don't sweat it, but it is worth considering.

Beyond that, I'd say choose the one you like most. If you like them both equally, I'd go for the cheaper option.

Off-topic: The new 1.2 looks pretty good with the new Sora groupset.