Very subjective....and it will vary widely from Maker to Maker. Personally, here are my thoughts:
EDC: Usually these are smaller, full time carry blades, so I tend to lean towards .140" or less
Tactical: These blades are expected to see harsh use, and above all simply cannot fail. Depending on blade size, I go with 1/4" or more for straight blades, and around .155" for folders
Combat: Same as Tactical
Kitchen: The thinner the better. The major concern with kitchen blades is ease of cutting for the user, and a long lasting edge
Neck: Just by virtue of how this type of blade is carried, it needs to be light in weight, so for me it's 1/8" or less.
Bowie: 3/16" and up, depending on the size of the blade
Utility: Generally 1/8"-1/4", again, depending on the blade size (length)
Hunter: I almost always start with 1/4"....but again, it depends on the specific blade, it's length, and intended use.
The common theme across the board is that the Maker should use the thickness appropriate for the given blade. All that being said, and the fact that 90% of what I do are forged blades, nearly everything has a distal taper....meaning that the blade is it's thickest at the ricasso, and tapers to the point, and again to the end of the tang. Distal tapers are a big key to giving a knife a "light" and "fast" feel in the hand. Distal tapered blades are also lighter and (this might raise some eyebrows).... stronger, then a blade of a single/given thickness throughout it's length.