My mood preferences and reasons:
Excellent
Weaponsmith or armorsmith
Artifact weapons and armor (excluding a single boot or glove) are both awesome and useful. Smiths are fairly hard to train, and quality matters more for weapons and armor than pretty much any other product.
Very good
Mechanic
I love artifact mechanisms. They make the shiniest wells, the most lethal traps, and an easy boost in room value that can actually be used for something when it isn't needed there. Mechanics are fairly easy to train, but I prefer to use only high quality mechanisms and sell all the others, so getting a legendary mechanic early on is a nice boost both to the value of my trade goods and to my supply of mechanisms that I'm actually willing to use.
Bowyer
Quality is far more important than material for ranged weapons, so I'm glad to get an artifact crossbow no matter what it's made of. A legendary bowyer is also good for providing lots of light, cheap, but high quality crossbows if I actually try to carry out my recurring plan to stick all my haulers and such in crossbow squads.
Good
Metalsmith
Gives an artifact that is usually valuable and useful. Hard to train. Good source of high value furniture, especially if I have some valuable but not useful metal ore on the map. I also like high quality anvils even though they make little or no difference.
Metal crafter
Gives an artifact that is usually useless, but valuable and fun. I like to have at least one high-skill metal crafter in a fort to provide high quality chains for wells, jails, and boosting room value. Also good for decorating weapons and armor, and sometimes I use metal crafts for trade goods.
Mason
Artifact furniture is always nice. A legendary mason help churn out blocks quickly for above ground construction, or uses up stone quickly from large amounts of digging. Also a good source for large amounts of high quality, moderately valuable furniture for dining halls and bed rooms.
Carpenter
Artifact furniture again. Speed is less important for a carpenter than a mason, since I rarely have huge quantities of wood to run through, but a highly skilled carpenter is the only source for masterwork beds. If wood is plentiful, it's also useful for barrels, bins, wheelbarrows, and light, cheap, high quality shields to go with the crossbows.
Leatherworker
Artifact clothing that doesn't fall apart is handy. I tend to buy up large amounts of leather from traders, so a skilled leatherworker to turn it into high quality items is nice, but far from essential.
Weaver or clothier
Artifact clothing again. I rarely get around to setting up much of a cloth industry, but it's nice to have the workers around who can do it properly if needed.
Mediocre
Miner
Artifact furniture is nice, but miners are very easy to train, and skill just influences their speed. I usually have legendary miners soon enough without wasting moods on them.
Tanner
Artifact clothing, but I don't tend to have all that much for tanners to do, and I usually allow tanning for a large number of my frequent idlers, so it gets done quickly even with low skilled labor.
Gem cutter or gem setter
Artifact is most often useless, and frequently a boring 'perfect gem', but sometimes an awesome piece of gem furniture. I rarely get around to doing much with gems, but skilled jewelers are handy if I decide I want to make some really expensive furniture or something.
Glassmaker on a map with sand
Artifact may or may not be useful. If I get a glass industry going, it invariably starts with churning out large supplies of green glass blocks, so glassmakers are easy to train if I need them. Having a legendary one on hand, however, lets me throw in trade goods and furniture immediately.
Bone carver
Artifact is probably not very useful, but likely to be amusing. I like having at least one high-skilled bone carver to turn my skulls into totems and churn out high quality bone bolts. If I have a lot of fishing going on, they can also use up shells.
Poor
Stone carver
Useless artifact. I tend to favor high value trade goods like ≡gold goblets≡, or most often rejects from my weapon and mechanism production that don't meet my quality standards. I usually do above ground walls, so stone mostly goes to my masons and stone carvers usually don't have a lot to do.
Wood carver
Useless artifact. Wood is usually less common than stone, and not valuable enough to bother with making wooden crafts for trading. If I happen to have a highly skilled wood carver and plenty of trees, I might make wooden bolts.
Engraver
Useless artifact. A legendary engraver is nice to have, but easy to get by smoothing everything in sight.
Die, you traitor!
Any Possession that produces a useless craft
Glassmaker on a map with no sand
