I avoid on purpose picking one of the starting seven for baron, unless i have a certain theme in mind for that fortress, i somewhat dislike the idea of them becoming nobles.
I check the dwarves' preferences as they migrate into the map, since those that like impossible stuff like anchovy bone and wagon wood (believe me, i had it happen) will join the militia full time before they even dare to run for mayor, and since i'm at it, i look for the best baron candidate, write down somewhere the name, or give them a nickname.
I found the less annoying nobles to be the ones with a liking for 3 or more craftable items (that aren't the main export of the fortress, of course), since more variety may mean less production orders and more export vetoes.
Favorite stone/wood/silk/fiber/colors/animals/penchant for decorations like squares, crosses, stars, circles, and phobias, don't seem to influence mandates or demands in the slightest (can anyone confirm this?), only the favorite metal, leather, bone and the item types seem to matter.
What i think are the best preferences for items: furniture, weapons and armor (if the place allows a good harvest of goblinite), trap components, mechanisms, statues, quivers (only if you have a source of leather), crafts (usually really easy to produce).
Preferences i do not recommend: large gems (unless the fort has a glass based industry, they can be a pain to obtain even from green glass), clothes (can't be remelted, if someone claims them can't be tossed in magma), bins/barrels/pots (so easy to trade them by mistake, and with 'culling on mandates' can't be brought to depot), crutches/splints (unless the fort has plenty raw materials, i hate to waste metal or wood on them), ballista arrows (this can be a boon, though, if you plan to use ballistae extensively).