EDH is more popular than anyone at Wizards of the Coast could ever have anticipated. Sets were not designed with EDH in mind until very recently. This was fine in most cases, however, since EDH is the "bulk rare format" - any durdle will do. Krosan Cloudscraper? Get on the bus. Boros Battleshaper? Actual gas. Most cards that Timmy loved ended up translating well into a slow multiplayer format with tons of mana ramp and nothing but time.
Unfortunately, the one drawback to EDH not having been supported until recently is a few cards could have made dynamite generals. Everyone has their card that they lament has no legendary status for the purposes of EDH. Reddit recently got ahold of the idea and posed the question - "Which existing character do you most want to see as a legendary creature?" This is both for the purposes of EDH generals and also just to wrap up some storylines or flesh them out more. Some of the responses were interesting.
Personally, I think the cycle of Nephilim should be retroactively made into Legendary creatures. The odds of them doing a second cycle of 4-colored creatures seems pretty remote and the existing Nephilim have great abilities that are predicated on them attacking or dealing damage which is tailored toward EDH before EDH existed. In fact, some playgroups allow Nephilim-based decks because the decks are so much fun and EDH has a community-enforced rule set anyway.
The best response I saw in the thread was Maelstrom Archangel which is hard to argue with.
How about you? Which Legend to you want to see?