This is going to be so awesome.
The idea of Meta Knight being a sparring partner is just so mindblowing. I do hope they get to be good enough to either A. Be an Equal or B. Kick my butt most of the time, but not everytime.
I like idea of two players fighting each other and they both use their personalized Amiibos to help them out. Each time the two players meet, the battles will never be the same.
I always liked the idea of putting stuff on my shelves related to things I love. Amiibos are small enough to not take up too much space, and they actually do something. I plan to work on getting quite a few of them.
Other characters I will probably want at some point:
Lucario - Another good choice for a character all about sparring while being awesome. After Meta Knight I'll definently get Lucario, unless someone awesome that has not been announced yet joins Smash.
R.O.B. - Now he really can be your Robotic Operating Buddy. I will definently get him after Lucario + Meta Knight because I am a sucker for Nostalgic things. R.O.B. may have been useless, but I still loved him a lot as a kid, and just liked having him out when I played games. So even if I never use the R.O.B. Amiibo, I will love to just have it just sitting around where I can see it.
As for the next 3, I'm not sure which one I'd get first for I love them for different reasons.
Wolf O'Donnell - I loved doing Fox vs Wolf (or Fox/Wolf dittos) 1v1 duels in Brawl (and Fox vs Falco or Fox/Falco 1v1 duels in Melee). However, I generally prefer to play Wolf, so if I get the Wolf Amiibo, I might get the Fox Amiibo too. I like Anti-heros that are basicly a better version of the main hero, and wolves are cool. So what?
Charizard - I do like the idea of a dragon kicking my butt. However, I'm not sure if they'll let the CPUs become that powerful. If the CPUs are weak, I may not get Charizard.
Link - One of the two characters that got me into Swords (other being MK), and one of my two favorite bow users (other being Pit), and I love his large arsenal as well. Link is also the most interesting character for me to watch when it comes to Brawl gameplay.
However, I might not get Toon Link, especially if SSB4 portrays Toon Link like Brawl, he'll be too childish for my liking. In Wind Waker he was always such a grumpy pants or had a "normal" expression unless he actually had a friggin reason to smile.
Pit - "The fight is on!". Bows + Daggers + Flight = Awesomeness. Goodie goodie two shoes act along with being a little ditzy at times is the only reason why I don't want his Amiibo so much. Personality can be distracting sometimes.
Samus (with Suit) - Samus just fits being a CPU when she's in her suit, and she looks pretty awesome in it as well.
While very unlikely, I might get Little Mac, Marth, and Ike. Marth and Ike only because I like swordsmen, and because they are fun to use in Smash (Maybe one day I'll play Fire Emblem so I can properly enjoy/dislike them). Little Mac because of Nostalgia. However, when it comes to Nostalgia, I think of the game and competitors in Punchout, not Little Mac himself.
I might even get Mii Fighter, but it really depends on a lot of things whether or not I'd get it. Would I be able to customize it's looks? Can I even choose which Mii Fighter it is? Or Would I have to get different Amiibos until I got the one I wanted? Or would it be random?