Check the player guides, specifically this one (or jump straight to my spreadsheet) - I've calculated how much experience per energy and experience per hour (plus gold/energy or gold/hour) that you can get with all of the missions in the game.

Basically, here are the "best" options depending on what you want:

Most XP/NRG: 102. Fresnel Cemetary - Blake Jones - Question the undertaker
Most XP/Hour: 115. Worlmen Sepulcher - Cultist Spirit - Rob the deceased (best w/both full or empty energy)
Most $$/NRG: 111. Worlmen Sepulcher - John Cathaway - Supply Run
Most $$/Hour: 106. Fresnel Cemetary - Liegh Branagh - Take payoff (if you start w/full energy - 30 second mission)
Most $$/Hour: 104. Fresnel Cemetary - Night Watchman - Raid mausoleums (if you start w/no energy - 2 hour mission)

The spreadsheet can help you find your best options if you haven't reached the last 2 campaigns yet. All of the numbers were updated this morning to reflect the updates.