I am in the US and had the same 2 bikes in mind when I ended up choosing the Halfway.
I had great experiences with TREK in the Past and my halfway was my first Giant. I cannot tell you anything about TREK, but I am very happy with my halfway for the past 6 months or so. Very solid bike and strongly recommended by most users.
What really sold me the bike was the customer service from the Giant Dealer. They were very supportive and helpful. I cannot say the same thing about Trek. Pretty much they laugh at you here in the US when you mention you are loooking for a 20"wheel.
Just my US$0.02
Rafael