Any of them except Cheerilee would be good grounds to question her sanity. But Cheerilee offers her nothing; for a Pegasus she’s already basically an Earth Pony, and she has the Ponyville vote. Her friendship with Tree Hugger is enough to get her the stoner vote already (assuming that just being Fluttershy wasn’t enough for that). And Flim? That’s almost as bad as Rarity picking Suri. So Discord by elimination.