None of these cards are mine. Of these, I voted for the middle 3 in the original contest. I'm not going to check my comments on them yet. Here's what I think of them now.
Druid - Really similar to Grand Market, which makes it less interesting to me.
Elixir - At first it seems sort of like a Treasury buff to me (similar to how Alchemist is a buff to Laboratory), but the more I think about it the more different it is. When you play it, you get to play (on average) half of your other Elixirs. That's assuming that you just have one Potion in your deck, which is usually the case, and no other Potion-cost cards. In this case, stacked Elixirs become a decent and reliable source of income. Other Potion-cost cards mess with this, for better or worse. Elixir also makes it a lot easier to buy more Potion-cost cards, since it will often keep drawing more Elixirs until ending on an actual Potion. I think it's pretty neat.
Enclave - This sets up all sorts of conflicting desires. Since it's a Potion card, you want to open with Potion and start buying it early. But it's terrible early on (barely better than Necropolis), before you have a good action density. Since it is a village, you want to play it earlier in your turn. But its draw effect means you want to keep it until later for bigger draw. I think this will make it very interesting and tricky to play. I think it can be very strong, but not brokenly so since it needs a lot of extra support and some good decision-making to work around the hand discard penalty. I really like it.
Incantation - Super simple. I probably voted for it in the past because it works kind of like Demonic Tutor, adjusted to work in Dominion. Now though, I think Transmogrify fills a similar niche. This is still neat, but I'm less enthused by it.
Research - Forge variant. The on-gain mitigates the cost of opening Potion, which I don't really like. The trashing effect also sounds too restrictive to be worth going for Potion. As a Potion card, it's slow to get going so it's poor if you're just after trashing (and the mandatory gain restrictions make it much harder to effectively trash Copper with it). So you should want it for its gaining effect, but it's so specific that I don't think it will be a good idea often. You have to trash exactly 2 cards, then gain something of a specific cost over it. Forge is much nicer since it lets you trash any number of cards. This contest shouldn't be judged by strength, but I think Potion cards should tend toward more power due to their opportunity and tempo cost. If this wins, I expect that the card would be more fun and interesting if the requirements were relaxed, e.g. "trash up to 2 cards".
Now checking my old thoughts on these, it looks like my reaction to Elixir and Enclave are pretty similar. I was more "I don't know" about Research. I was more positive on Incantation and Druid.