Not instantly familiar with either, but a quick look at the fathom 2 online; decent entry level rig, Deore drivetrain is adequate, geometry looks modern, price is right. In general Giant bikes are a good value.
Their full suspension rigs are on sale now too, some killer deals. Not sure if you think it'd be worth it to you, but FS bikes are pretty great these days. If you think you'd ever get into trail riding, it'l might be worth it.
Giant FS bikesETA.
The Trek looks basically comparable, Sram instead of Shimano, but the Giant has slightly more reach, a bit slacker headtube and a dash shorter chainstay length, a bit more progressive geometry than the Trek.