I have asked that specific question and gotten the run-around. Trying to read between the lines it appears to be Marshall over Lillard.
If I had to guess, I would guess Marshall would appeal more because he can run an offense and make others around him better with his elite passing. He's also got a bit more size and played against higher level competition. Putting Marshall on the floor with the other young players (who can all score) should be all the offense any team needs.
Hope the Jazz will get both Lillard and Marshall in for a workout though.