granted, it is absurd how available the tomes are during bg1 (especially for WIS of course) and how 'balanced' (as in one recipe for each stat, otherwise quite 'unbalancing') the machine's power is. i'm hopeful about fields of the dead actually putting them in - shall we say
much more secure locations?
i generally prefer iwd2's potion/tradeoff approach. but 90% of the time i'm pretty munchkiney about the tomes/machine.
to wit, i can always afford to give one of the giant-strength girdles to imoen. permanent STR boosts go to charname if they started with anything over 14 or under 9, otherwise a fighter-type. taking utterly fair use of SK into account (i.e. carrying over bg1 npc stats) it can be nice to have two S 19s in the party without acquiring a girdle. (even though my personal view is that the whole exceptional-strength scale is very annoyingly bungled by this engine [though not so much with torment, i was pleased to note]; was never terrifically appropriate after 1e came to a halt; and died a righteous death in the fire of 3e.)
charname always gets the CHA boosts unless s/he depends on the ring of human influence - then it's a toss-up, although it'd never go to any of the bioware dwarves, nor most of the males for that matter - ajantis or coran perhaps, but more likely imoen or safana.
and always the DEX unless it's not going to make a substantial difference (taking sacrifice/s into account) - in which case the book goes to coran if he's there; any other circumstance, it's for any of the under-18s except keldorn, anomen or edwin.
imoen, edwin, nalia can squabble over INT (once arcane-charname has 19, if applicable); i might give quayle, aerie, jan or a bard a shot at it.
WIS mostly went to branwen, but i never used to have much flexibility between bg1 campaigns; i'd consider giving viconia, xzar, faldorn, yeslick and/or jaheira a dose as well - might even give minsc a couple for the times he can't rely on the daily berserk.
if CON won't particularly help charname, it goes to whatever dwarf happens to be along, but any of the fighter-types are excellent candidates. or jan or kelsey, even.
i've done party-wide mental-banter with the Machine recipes a couple of times, but with tomes only once: safana 'talked' charname into giving her the CHA booster because she'd 'let him' have the CON from the hidden stash. meh, i was lonely and gullible.
after careful reflection, i'd consider giving
all boosts to garrick in an experimental run, except then i'd rather eliminate him from the temple district... (and drag him along multiplayer style). never could bring myself to bring him through a whole bg1 run before. ridiculously enough he lasted the longest when charname was a bard.
something i wondered about but haven't checked up on: does bg2 include the immunities granted by over-18 INT (illusions) or WIS (mind control et al.)? (this was possibly only ever a 1e arrangement; 2e documentation isn't springing to mind and i don't have any of 2e's relevant works at hand)