I haven't bought any yet, despite me wanting to, because I refuse to put money into the damn scalpers who want to sell me an Amiibo at double or triple the retail price because it's popular or in high demand. You, too, Nintendo, need to either make more of these little buggers or I'll boycott your Amiibos like I did Apple's iPod Touches (a boycott which ended a week ago after 5 years).
If there were any Amiibos that I would immediately want it's the Splatoon set (Inkling Boy, Inkling Girl, & Kraken). I enjoy the game and having some extra side missions, gear, and weapons will only add hours of fun to an already awesome game.
In terms of purely collecting them because they look awesome, it would be Mario, Fox, Samus, Charizard, Sonic, Megaman, Pac-Man (my mother actually wants this one for her desk at work), and, in the future, R.O.B. and a Green Woolly Yoshi.