I would have to say I think Nico, Aaron, Colin, Evan?, Leo, (idk next two), (idk Cameron Todd)
But there's gotta be some bias in knowing how well Nico and Colin have moved on to college, it's hard to consider exactly them in high school. Nico only 8:40 3200m by then. But then again Jojo Jourdan ran exactly that too at same Arcadia meet, AND not solo like Nico did. I think Nico grinds it out in XC.
I think at peak form, Aaron Sahlman's NXN performance wins out over Drew Griffith. Just crazy dominance and course record. Dunno if he'll ever replicate that race of his life though. And maybe it only looked so good cause Young Twins scuffed their pacing.
Colin Sahlman arguably has just about the same endurance as Danny Simmons but I'd take him for the kick every time. 1:48 800 speed with no comp except brother chasing him down, and all of his sub 4 feats and stuff.
I'm not sure if Evan Noonan is really at Lex's level at all yet. 4:06 in the 1600 is no joke and a good Arcadia 3200 mark but 8:47 is far from Lex level, with lex going 8:43 and then 8:35 in sophomore and junior year. National high school 5k record holder takes it.
Now Fast Horse and Leo Young is another one that's just like recency bias if you pick Fast Horse. There's no way he's close to Leo, even with 14:32 Clovis, Leo has 3:39 1500 speed and ran 14:25 Clovis too, and just has more impressive feats in high school so far. Not saying it can't change if Fast Horse has a crazy season but it isn't looking like that so far. Fast Horse 8:45 3200 to Leo's U20 worlds performance is night and day ;-;
Can't really speak to these last ones though.