Even When They're Not Around, They Manage To Piss Me Off

Xion Zolvhur, obviously, because he was the only Ancient Designer Jake currently had any relationship with, his will fragment having enabled Xi to break free from the Oracle System. Vexa, because he was a distant descendant of Aas.

The Cube Ancient Designer was supposed to cover all costs related to the Ordeals, and the Oracle System's recurring malfunction since the start made it the prime suspect, besides the Digestors of course. Or at least, the first one Jake needed to consult about this matter.

Alas, Jake hadn't yet reached a level of power or renown where he felt entitled to meet an Ancient Designer just because there was a 'minor incident' in one of the billions and billions of Ordeals involving their Mirror Universes each day. Even meeting an Oracle Overseer was probably above his pay grade.

Which brought Vexa as the second choice.