I've received the elephant, duck, butterfly, snail and UFO (rest now on their way 
) and I would say that the elephant is the best as well. But DH thinks the UFO is, because the mechanism is "very clever for a little thing like that". Which I think will be lost on littlest DS, but elder DS who likes gadgets will appreciate how it works. I guess it depends on how old your DC are.
I think the second best is the duck, because he seems to do quite a lot as well, he's off in different directions, sort of spins and lurches about like he's pecking. Then it's a tie between the snail and the butterfly. The butterfly DD will love because it's so fluttery. But the snail is just plain funny, it's so bloody fast, and it's neck bibs in and out as it tears off. I don't know why this is so funny but it is.
I haven't found these ones anywhere else for this price, but it kind of depends how fussed you are. Because we keep ours and build a collection year on year, we look for the most weird and different ones we can. Basic chattering teeth, or those generic santa/penguin/racing reindeer that just sort of shuffle along wouldn't cut it here, don't you know 
I'm pleased with what's arrived, so I've ordered the rest now in case these become even more hard to get in subsequent years.
I've always used a local toy shop but have had to look elsewhere hence the difficulty in finding these. I have found some others previously in a Christmas Craft Fayre, and then sometimes at places like farm shops when they do their Christmas section. Which I know is not much actual help, but if you're going to anywhere like that, keep an eye.