I'm not impressed with FE Deluxe Optimus even a little. The bland painted windows just ruin the aesthetic for me, though his articulation and gun are quite nice. If you have to pick between FE Deluxe and PRiD Voyager, I say go with the latter. He's pretty solid, poses well (though lacks the waist swivel), and I love his lightpiping.
Of course, if you can wait a few months, I say go snag FE Voyager Optimus, it's the best of the three by a long, LONG way in robot mode. The altmode is...really rather weak though.
In terms of altmode, I'd rank PRiD voyager highest, FE Voyager lowest. In terms of robot mode, I'd rank FE Voyager highest, FE Deluxe lowest.
Of course, there's also Generations WFC and FoC Optimuses, for something completely different in the same character.