I love both of these songs dearly, and admittedly, this is one of the less mindblowing B'z singles (which isn't to say I don't love it). As kyuu said above, the guitar that Tak brings to the table here is kind of insane--you just have to see it live
to understand how magical it is.
[spoiler]Did I deliberately choose the one performance where Koshi had to go back to his old days before the song even started? Yes. Yes, I did.[/spoiler]
Going by animation, I would say TRUTH has the edge given that it wasn't recycled--but B'z is actually in the girigiri opening, so... Tough call! I'll still go with girigiri, naturally, but I understand people picking TRUTH (as in--my hitmen aren't on the way to your residences just yet, but if ONE loses by the time we get to movie themes, expect a man to come flying through the window at any moment).
By overall song, though, to me there's no question that girigiri is the better tune. Especially the solo... Oh, the solo! So wonderful, I am a fan.