I'd go with the GT. Tiagra is a much nicer, higher quality groupset than 2300, and the shift levers are especially more comfortable. Additionally, the Giant comes with a triple crankset, which, in my opinion, is unnecessary, and at this parts quality level, will only weigh you down and make self maintenance more complicated. I know several people with triple cranksets, and they hardly ever use the granny gear. The gearing on the GT is traditional cyclocross gearing, which is low enough to be comparable to triple gearing, without unnecessary complication.