Troubadors do CA and Spell damage. The effectiveness of their CAs (Combat Arts) is based on STR because it is essentially mele damage. Spell damage is deturmined by INT. Your power pool is increased by increased either of these two stats as well.
AGI is important for every scout class because of their avoidance bonus. For my troubador, i have STR and INT as high as possible because i mostly group with him so shouldn't be getting hit, which is to say i shouldn't need as much AGI or STA.
Of course, if you plan on soloing, you will want a balance of all four. I would say for soloing, the order should be INT, STR,AGI, then STA.
But also remember, a troubador is not a pure DPS class. It is a support/utility class. Your main focus in a group is buffing the damage output of the mages and increasing power pool and power regin.
You will have very annoyed group mates if you are trying to go all out damage and ignoring your buffing duties.