There is supposedly a way in which you can get combat to almost pay -comparatively- to cargo, but it requires going really out of your way to find a system with a lot of factions all handing out pirate kill orders to the same faction. This is really rare and non standard, but I well definitely agree that payouts for combat are horrendous.
Non-combat
Mining - 170 m/hr using a fast ship and selling to the right place (may not always be available but should net 100 mil/hr when the market falls)
Wing Source - 140 m/hr with a wing. This is approximate based on what my friends and I have done. Finding stations that provide enough missions for this is not hard.
Exploration - 100 m/hr, unverified but I keep hearing there are certain paths to follow and scan to rake in huge sums, but this requires a high exploration rank.
Transport - 80-100 m/hr Is supposedly the Robigo standard but I haven't personally verified this one either.
Combat
MultiFaction Pirate Mission Stacking - 100 m/hr. Requires a system in which pirate hunting factions are numerous but pirate factions are minimum. This requires a lot of hours investment for a session and significantly more hours to hunt down an appropriate system.
Pirate Massacre one-at-a-time - 30 m/hr
Assassinations - 20m m/hr, possibly a little more when stacking wing missions with wing mates.
Conflict Zones - 1.2 m/hr, provides virtually no incentive to participate in over the inf, rep, mat, and credit rewards provided by missions.