Help me with some new button designs!

[Sheeta]

So Midwestria is coming up in a few weeks here in the northern Illinois area.  I plan to sell my art in the dealer's room, and one of the things I love making are buttons.  For the convention I plan to have a good run of "[insert character name] Is Best Pony" buttons, but I'm having trouble deciding who makes the cut for the current round.  

This is the cast of characters I have so far:

First round (already done):
Mane 6 (a couple designs have been reworked)

Currently being worked on:
Discord
Spike
Queen Chrysalis
Derpy
Zecora
Crackle the Dragon

Likely to be done:
Vinyl Scratch
Celestia
Luna
Octavia
Trixie
Big Macintosh

This is where you guys come in.  Who would you like to see as a button design?  As of now these guys are on the "possible" list:

Cutie Mark Crusaders (don't know if they should be done together or separate)
Granny Smith
Dr. Whooves
Nightmare Moon
Pinkamina
Twilight Psycho

Note--each button is 3 and 1/2" across.  Give me your input!

[Magna]

Dr. Whooves, definitely. Maybe a Gilda and a Discord.

[Shim]

I see you mentioned Big Macintosh. Well, I would suggest Big Macintosh and Big Macintosh again !

[Ziel]

I won't be there, so take my input with a grain of salt. But I'd vote Dr. Whooves and the CMC from that list. Also, Lyra?

For the CMC, if the size works for it, I'd probably put them all together. You could also do the CMC Logo either along with or in place of one with the actual CMC on it.