I had no interest when they came out but then realized they are a good representation of a lot of Nintendo's history and wanted to start, but some of the ones I most wanted were crazy expensive. Not much later they started reprints and I jumped in. Now according to Amiibo Life I have 136 figures, with two more arriving Friday, and most of the cards.
As I like having them as a visual of Nintendo history, some of the more obscure characters are my favorites such as Wii Fit Trainer and Box Boy (whom I felt a bit silly for buying for $40, had no idea it's worth so much now).
I've never cared too much for their in-game use but every now and then something would come along I enjoyed like the costumes in Mario Maker, Odyssey, and Woolly World or the Samus Returns stuff (which should absolutely have been put on the eshop).
I was really happy with the release pace back a couple of years ago, where a game would get a figure or small series like Kirby, Samus Returns, Fire emblem Echoes, Woolly World, the various Zelda series, and Mario Odyssey. Now, sadly it seems like it's mostly just the Smash line. I wish we'd gotten a Captain Toad and Toadette with the Treasure Tracker port or a Luigi, Gooigi, Egad, Polterpup series last month. I was stoked about the Link's Awakening release, that's one of my two favorite figures now.
Coming down the line I'll get Richter and Dark Samus, Banjo, and maybe Terry. He doesn't have much history with Nintendo but I just kind of want to get that one regardless. And I hope we do get all four Heroes. If there's a Direct in January I hope we get some good Amiibo news.