Mine was the one that I put on when I hit legendary necromancer:
Hero of Unicorn Way.
I have never worn a badge, but I told my wife I would put that one on when I hit legendary. I actually like not wearing one, as people can discern who you are more easily. Of course, I look like I am level 5, as my WT crafted hat has been stitched to look like my Novice hat. haha. What can I say, I like the look of the wizard I was when I started out.
Dragonspyre Master (my favourite world, of course); Sword Saint (I like swords, simple as that); and Saviour of the Spiral (R.I.P. Sylvia, Malistaire, and plot).
If I were to run around with my actual title ("archmage sorcerer") on display, especially when passing through the Commons, it's like waving a red flag at a bull~ as in, it practically invites random level 10s to spam friend requests at me as I wander towards the Bazaar. I have stitched WW gear and, at a glance, appear rather unassuming... unless I'm on my Hydra, with fellow archmage wizards in crafted Avalon gear, in which case it's pretty obvious that I'm level 80. ;)
-El Veeb/Shadowsong Sword Saint, Dragonspyre Master, & Saviour of the Spiral (also a shameless Drake fan-girl and collector of oddities)
From the end of Unicorn Way to level 22 on my Ice wizard, my favorite badge was Hero of Unicorn Way, and then at level 22 I wore the badge Savior of the Spiral until I finished Dragonspyre, and now my favorite badge is A+ Student.
If I had to pick one for each school: Ice - Cold Iron Warrior Storm - Technomancer Fire - Yojimbo (Thats what I have right now :D) Balance - Emerald Champion Life - Weed Whacker Death - Ghostbuster Myth - Either Unbearable, or Blood of the Giants.