There are some strong considerations here. The evoke creatures offer a superior sort of way to do things that staple sorceries did in the past. I'm the sort of player who generally balks at using artifact-removal spells in my deck, but I wouldn't hesitate to use Ingot Chewer in a casual deck. These cards are great, and Shriekmaw might be the best representative of them. I've always preferred Diabolic Edict to Terror, but Shriekmaw is still impressive. There's Thoughtseize that gives us a strong alternative to Duress (or a way to run more copies of that effect). But that may not be fancy enough for a casual hall of fame. It's pretty cut-throat. Along the same lines, Ponder is good, but is probably thought of as too much of a competitive card to be a casual favorite. And it doesn't do anything new or special. It just does old stuff well. There's Oblivion Ring, which immediately stood out to me when looking at the set list. Al0ysius and I (mostly me) made a list of our top 200 enchantments for our blog and when I realized an error I'd made left an open space, I looked at cards that should have been on the list, but that we'd accidentally overlooked (mostly from newer sets). Oblivion Ring was the card we chose. It's a fine take on removal, I think. I was also thinking of Pestermite for combo goofiness, but it's probably not as strong a consideration as the others.
I was sorely tempted to nominate a merfolk card, probably Merrow Reejerey. This wouldn't be for the reasons I've normally nominated cards. I like the idea because the mefolk from Lorwyn heralded the return of merfolk as a force to be reckoned with. Before the word "tribal" was being thrown around and Onslaught made creature type so important, there was a period of time when merfolk were the strongest. And I was nostalgic for that. Goblins, elves, and zombies shot ahead of other tribes and became so much more powerful. Merfolk weren't even close anymore. They weren't getting new stars in their ranks and the old ones couldn't compete with what new sets had to offer. Lorwyn and the sets that followed it have put merfolk back where they belong: on top. Seriously, they are the strongest tribe now. I can't believe I'm saying that. I still can't wrap my head around the idea of goblins not being the strongest. Although to be fair, Goblin Recruiter is banned in Legacy. Even so, it's the new merfolk, like Merrow Reejerey, that have changed things so dramatically.
However, planeswalkers have added a new element, if not a new dimension, to the game. I was initially displeased with the whole idea for flavor reasons, but mechanically, planeswalkers are an ingenious addition to the game. And Lorwyn was the first set to have them. I really believe that a planeswalker should be the inductee for this set. But which one? Shabbaman mentions Liliana Vess, but I can't tell if he's nominating her or nominating Shriekmaw. I am torn between Liliana Vess and Garruk Wildspeaker. The former is appealing because I like black cards, but the latter even moreso because of its use in Death Loam decks (one of my favorite decks for Legacy right now).
Vess costs more, but does have two more starting loyalty to make up for it. The Disrupting Scepter effect is very nice, but Garruk's mana boost beats it and is one of the strongest abilities on any planeswalker I've seen. Costing only four mana and producing two mana for you per turn while generating loyalty is just plain awesome. Both planeswalkers have excellent second abilities. Garruk's token-generation is cheap and powerful. Liliana's tutoring is costlier, but so powerful that it's even better. Garruk uses an ultimate that works really well with his tokens and other creatures and can easily finish off an opponent. Liliana goes a different route, with an ultimate that is hugely expensive, but so powerful that, barring graveyard removal by your opponents, it should overpower anything.
I could happily nominate either one and I think it, to an extent, comes down to mood. Since Shabbaman might have already nominated Liliana Vess, I'll nominate Garruk Wildspeaker myself, so if both are nominated, the committee can figure out which one (if either) wins.