Two uses for potions of genius. First, to increase the chance to learn spells. Second, to increase lore - really, using genius potions to increase lore is just a convenience, as the identify spell will ID anything.
Obviously, the stat-increasing potions are more valuable if you have low stats. Some parties will need potions of genius, strength, agility, fortitude, etc for spell learning and combat effectiveness, and some parties with better stats can just sell those potions.
I don't think that any dialogues are Wis-dependent, and since the effects don't last long, the Wis potions don't give a spell memorization advantage. Other than temporarily increasing lore, there's really no purpose to them.
DON'T sell your potions of clarity. They are critical for a later portion of the game. I can spoil you as to the area if you want.
In general, I don't use many potions and I tend to sell more than I keep. Hold onto potions of extra-healing, antidotes (or elixir of health), mummy's tea, magic shielding, giant strength, clarity, absorbtion, invisibility, and whatever offensive potions you think you might need (potions of explosions, fiery burning, firebreath, speed).
I always sell potions of infravision, insulation, defence, stone form, perception, and mirrored eyes. If you have too many duplicates (e.g. of heroism or fire resistance), don't be afraid to sell some of those too. If you can fill 3 potion bags, you can safely sell some.
