How much do you "need", assuming no megaprojects? And assuming quantum stockpiling? I survive just fine with:
Artisan Class (dedicated crafters), Military Class, and Serfs. Artisans have almost all other labors turned off except their primary skill, military class trains 24x7. Serfs do everything else.
1 dedicated planter (yes one), all other serfs harvest plants from the farms. This same dwarf also tans hides, butchery is enabled on all serfs.
1 cook and 1 brewer, they work full time. At legendary skill they have pretty much out-crafted a full fort of 200 for several years already.
2 builder dwarfs who do nothing but carpentry, masonry, and glassmaking/glazing/pottery at dedicated workshops to produce quality items, with other shops available for high-speed serf construction if necessary (need 36 beds right now!). Normally serfs have masonry enabled for constructing walls/floors topside in order to get well walled in.
3 miners (I actually prefer more but 3 is enough) to keep the stone and ore flowing.
1 burner (furnace operator) and 1 metalsmith (armoring, weaponsmithing, and general smithing labors).
A few military (totally subjective, whatever you want to spare for an army... or none)
A few serfs for hauling and every other miscellaneous duty, and all those labors stay enabled on them. All serfs carry an axe for woodcutting, none double as military.
This is VERY minimalistic but it fills my needs. I usually make a full two-squad military and have around eight burners, a dedicated armor and weaponsmith (stays busy with bolts), a dedicated generic smith for furniture and goods and studs, a dedicated large pot maker for food/booze storage, a dedicated hunter, a dedicated fisherman (this dwarf is usually the first to die to any given threat), and about 6 total miners because I love the metal industry.