| OdeonAX |
I haven't done the math to check but having seen both a zen archer (monk)/inquisitor and an eldritch archer (magus)/slayer (or ranger) in action I think they're pretty evenly matched in terms of damage output. They also both have all good saves and 6+ skill points (which makes them good all around gestalt combinations). IMO the EA/slayer has a slight advantage in that it has a real full BAB and d10 hit die to the ZA/inq's sometimes full BAB and d8 hit die (EA also keeps fighter training which opens up weapon specialization and other goodies). That's in general; for your party specifically, it looks like you'd benefit more from additional arcane casting than more divine (as others have mentioned) so I'd definitely suggest the eldritch archer/slayer. That's also a better fit for Tiefling I think.
I can post a potential build for you but before I do: are you allowed to use prestige classes at all? or multiclass in any way? I haven't given it much thought yet but there's probably some cool options available once you throw arcane archer into the mix...
yes, we're allowed to use prestige classes, and now i'm thinking of a EA/ mutation warrior, seems cool..