I honestly don't think you could go wrong with either of these. If you are able to ride both to compare that'd be ideal. If you're picky about having the same components then go with the Trek.

Also looks like the Spec has hydro discs vs rim brakes on the Trek. If you ride under wet conditions the discs are better, but it'll make the bike heavier than the rim-brake counterpart.

Edit:
As a second bike, I'd probably choose the Trek seeing how you already have the FX as a first bike with disc brakes already.