As grilla, i bought the Defy 2, 2012 model for £650, mainly because of the better groupset and the frame and forks get really well reviewed.
It is a very stiff and responsive, you feel the bike pick up straight away, I tried the Triban 5 and did not find it quite so responsive, it is still great value for money though.
I would try both and see what you prefer.
I swapped the seatpost out for a carbon one to make the Giant a tad more comfy.
The Giant has carbon forks as well,
it is the seat stays on the Triban which are carbon and alloy on the Giant.