[Rataxes]

Only DEX, CON, WIS and INT can be sacrificed.

I'd personally choose INT since there are more than enough Potions of Genius/Mind Focusing in the game to satisfy all your intelligence needs. Though STR isn't all that important either due to loads of STR-enhancing items. In fact, if you got anything less than 19 or 18/00 STR, you should aim to get a STR-enhancing item as soon as possible anyway.

Neither WIS nor DEX are good choices, so it would either have to be INT or STR if it were up to me.