Alchemist-

You want this perk.  Everyone wants to be an alchemist, since it uses the resources you can collect for free everywhere that don’t weigh very much, and having more potions at the least is always a very good thing.  At its highest rating, this perk alone can double the effectiveness of all your concoctions, keeping your potions relevant through the middle game.

Physician-

Potions are even more important than poisons, particularly because poisons are one hit per dose and can easily be wasted, not to mention that some enemies are resistant or even immune to some poisons.  That makes this perk invaluable to both budding potioneer and expert apothecary alike.  If you use ingredients to make potions at all, you want or even need this perk.

Benefactor-

Stacking with Physician and going further to also enhance your skill potions, strength potions, and various other positive draughts, this perk is even more valuable than its prerequisite, and will ensure that you can always make something useful from this and that and a couple of these here.  Take it, take it immediately.

Poisoner-

Less valuable than the potion-related perks, this is still a very nice perk to have if you bother applying poisons at all.  Keeping in mind that heavy poison use means frequently pausing combat by dropping into your item menu to apply new substances to your weapons, this perk can still be quite effective at helping you topple your enemies and keep them down.

Experimenter-

While there’s a lot to be gained from mixing things to see what happens, there’s nothing quite like putting together a Potion of Healing that cures 50 Health only to discover it’s also a Stamina Poison that will kill your Stamina regeneration for 20 seconds.  It’s a painful experience, sometimes a complete waste of ingredients, and can eventually become highly aggravating.  Experimenter lets you avoid that by making sure you get the chance to figure out most or even all of the things each ingredient does before making a potion that refills your Magicka but paralyzes you for ten seconds when you sip it.  If you want to really invest in making effective poisons and potions, you want this perk badly.