The more valuable the potion, the more experience you get for making it.
Blue Mountain Flower, Blue Butterfly Wing, and any number of ingredients too long for me to remember effectively since I haven't played in months. Those first two are a base potion, but you need a third to make it exceptionally good. Wheat or Giant's Toe are pretty good.
Paralyze (the round swamp fungus, Canis Root) potions are good too, and Slow (Salt, Deathbell).
Hey Ike, as people said this would go in the Tips and Tricks Group (more specifically the Questions/Requests Thread.) In the future just check out the Where do I post stuff page which gives a general rundown of where everything goes. Because this is in the wrong spot I'm going to delete it within either 24 hours or by the time you comment on it next.