The most popular potions are probably not the ones shamans use, since we are only a small fraction of the population.
For most classes under level 65, I would guess that SoW potions are still the most popular; but I don't make these any more, leaving this particular item for others to make and sell. They are cheap to buy; they provide a genuinely useful effect; the effect lasts a long time, so they are a good value. But as a shaman I never use these at all.
I have made the most money from Gate Potions. I don't make them to sell any more, but I still get more requests from guild mates for these over any others. They are considerably more expensive; they have a useful effect, but they take a long time to cast so they can replace a port but can't replace an evac; still, when you need a Gate Potion you really really do need one. But again as a shaman I never use these at all.
For my own use I carry usually around 40 HoT potions and 20 kei potions.
The HoT potions are in slot 1 of my potion belt, and I will generally use 2, maybe 8 to 10, most every time I am soloing; when a couple of adds show up it is very useful to slap an additional instant-cast HoT on myself without needing to retarget. (Slot 2 of the potion belt is a Vial of Swirling Smoke.
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I probably use 1 or 2 kei potions a week, but I end up giving away 8 to 10 each week to group members who have died and been rezzed and there's no enchanter around. Most of the people I group with carry a stack or two themselves; the give aways usually are for the random-sixth-player we have picked up.
There continues to be a small-but-noteworthy need for other utility potions: shrink, levitate, damage shield, FT3. Improved Invisibility would be an expensive but steady seller if there were any reliable way to get the ingredients.
