Food efficiency
This section is about figuring out what station is best to use in your current condition to farm food. It will get very technical and mathy so if you don't care about max efficiency, you don't need to bother with it. Special thanks to Battle00333 for their screenshot and explanation on how it works.
The below table contains "the normalized effective food rate per hour per unit for each station according to the producers used". In more understandable terms, for each tier (see below) of minions, this is the effective food rate a player can earn using each station at each level, neglecting cravings. Bigger numbers means better. This information will naturally be modified by bonuses, but it is simply a tool of comparison on how much difference there can be between different tiers and stations.
| Tier |  Mana
|
 Slime
|
 Darkness
|
|---|---|---|---|
| 1 |  Skeletons
|
 Zombies
|
 Mummies
|
| 2 |  Eye Monsters
|
 Spiders
|
 Bats
|
| 3 |  Banshees
|
 Ghouls
|
 Imps
|
How to read the table: The player has a 
skeleton v7 generating 
mana , this is a tier 1 generator, so the first line section (with the bone, paper roll and meat) is the one being read. Since mana is the resource here, we look at the graves and lectern colums. Let's say the player has enough space to fully merge any resources up to their max level minion, and has a grave v5 and a lectern v3, which one should they farm to maximize food if no mana cravings are present? From the 5th line of the tier 1 generator in the grave section, we can sum up the food from skeletons (0.90) and the food from zombies (12.05) for a total of 12.95. In comparison, from the 3rd line of the tier 1 generator in the lectern section, we can sum up the food from skeletons (1.27) and the food from banshees (5.63) for a total of 6.90. We also get 33.75 darkness from feeding the resulting shades. The comparison gives us that a grave v5 is more efficient than a lectern v3 for food in this context, since the player would get 12.95/6.90 = 1.88 = 88% more food. We neglect here the resulting darkness, but the comparison can be done including it. Is the player willing to sacrifice 12.95-6.90= 6.05 food for 33.75 darkness for every unit of mana generated (the value that is indicated when you tap on a minion), per hour? If the answer is no, then they can use the grave, otherwise, the lectern. Naturally, all of this math becomes wrong if the player starts tossing parts to the devourer for space, but only by a slight margin. See below for the full chart, made by Battle00333 (they gave us permission to post this here):
(Click on the image to enlarge if needed)