Harriet amiibo, because she's soooo cute! :') Villager wise, well, my favourite villagers are Chrissy and Francine, so I'd like to see them added. I don't know if they will make them, though. There's a chance they could! They've appeared in official Nintendo advertisements before, and on merchandise, etc etc.
Imagine the horror if they made amiibos for ALL of the villagers and they were similar to smash amiibos. Some are rare, some are not, they barly exsist and they come out in diffrent waves xD
I think it would be a clever idea for Nintendo to make at least one amiibo of each species. They could hold a poll and let the fans vote for one villager of each species and the one with the most votes is what is put into production. I'll probably never see an Ed amiibo, though he'd be the one I vote for out of the horses, but at least people would get to play as the species of their choice, even if it's not the exact right villager.
OR, Nintendo should have a sort of shop where people can order custom amiibos. I've never tried to buy even a regular one before, but I see a lot of people talking about how Nintendo isn't keeping up with demand anyway. So why not just charge people a little extra and make each one to order?
I'm going to be the first to say that I'd probably literally faint if Pete was announced as an upcoming amiibo. He's my favorite character and I feel like he doesn't get enough love.
Other than that, Blathers and Kapp'n are my other top picks. Blathers I feel like definitely should have been put in, he's been here from the start and he's a pretty popular character.
I'd like to see Tortimer as an amiibo - I feel like he's a really important character who deserves one. Slightly less important but Blathers and Resetti would be great as amiibo too I feel. I would certainly have expected them to get amiibo before Digby.
As for villagers, I'd go crazy for Kid Cat, Agent S and ?oco especially. I love all of their designs!