Actually, even though Spirfindel has good stats, low threat, good action advantage, and potentially great leverage on location heavy APs I think he's still less ubiquitous than Eleanor. People who don't play multiplayer won't readily understand this statement. But any group of three or four players know how much more important Eleanor is than Glorfindel to player success. She may not have as much individual synergy in a given deck(in fact she very often has no synergy other than her sphere) but is necessary to keep treacheries from hosing the players EVERY turn. Her threat is similarly low like Spirfindels, but the only thing you can readily spec her for is defense with a shield. Beyond that she just kind of gets in the way of individual deck synergy.
Say what you want about Spirfindel, but his ubiquity springs from his uber-synergistic qualities. Not a statistical mandate of the encounter deck. Playing with three people? On average your going to get hit with a nasty quest disrupting global effect EVERY turn, unless you play Eleanor. I was actually experimenting with spirit Pippin in a threat dropping deck, but I had forgotten that in three and four player one must carry the burden of Eleanor.
Looking ahead to the coming AP, I know there's an emphasis on Unique allies. I think an exact copy of Eleanor as an ally would do wonders for this issue. Hell I'd be happy with a copy that had two hit-points and 0's in every stat so long as it kept the ability. The only other multiplayer option I've seen is utilizing decks with scout ahead and the door is shut. I haven't tried it, but the limit one per deck rule makes it look like a very involved strategy if you want to use it for consistent treachery nullification. Has anyone had success with this sort of strategy?