This article is mostly meant as an addendum to Fame and Fortune. All potions listed here are PFS legal 3rd level potions, meaning they are available as 2 PP purchases. The most important ones are Fly and Remove Blindness/Deafness.
Cure Serious Wounds – Heals the drinker for 3d8+5 hp, or 18.5 hp on average. Alchemists with the Healing Bombs discovery should consider having one of these on hand. You could ready an ‘attack’ against an ally on their last legs getting hit to keep them on their feet.
Remove Curse – Allows drinker to roll a d20+5 against a DC of the caster level of whatever cursed them.
Remove Blindness/Deafness – does what it says. While more specific in its uses than remove curse, there is no roll against caster level needed.
Remove Disease – roll a d20 with a +5 modifier against the DCs of any and all diseases effecting you to cure them.
Neutralize Poison – same deal as remove disease, but for poisons.
Protection from Energy – ignore the next 60 points of an element’s damage to you. Lasts 50 minutes. I think you can choose which element when you drink it rather than when you buy it, as you choose with the spell at casting rather than prepping.
Magic Circle Against [alignment] – This one does enough stuff that you should just read the description in the link. One would likely buy one against Evil, but Good, Lawful, and Chaotic are available. The alignment actually must be chosen at purchase though, not upon drinking.
Fly – You can fly at 60 ft. speed for 5 minutes. In a straight line that can take you a total of 6000 feet with all ‘double-move’ rounds.
Water Breathing – 10 hours of safety from drowning is nice, though I’d probably just stick to air crystals myself.
Heroism – Grants the drinker a +2 morale bonus on saves, skills, and attacks for 50 minutes. I’m not usually a fan of spending money on these kinds of buffs (I usually save PP for things that will save my bacon in weird situations rather than pure numerical bonuses) but as a pre-buff for a tough dungeon, this is undeniably good.
Tongues – Breaks all language barriers for 50 minutes. Not too shabby for those situations that call for a translator.
Those the best potions for PP expenditure I’ve found. If summoners can make potions, Evolution Surge would be an incredible one. I don’t know if they can though, or if that would cost more.