I prefer speed to ath for my guards, and even SFs...but that's just me. I would recruit a 80 SP 30 ATH guard, but I would never even consider a 30 SP 80 ATH guard. In D3 I've seen plenty of successful guards with ATH<50, but I've never seen a top team with sub 50 SP guards.
That said both attributes are clearly important, and you can have success emphasizing one or the other...but don't expect to have success with low SP guards IMO, regardless of ATH.
And just to be clear LP definitely is used by guards now, that was changed several years ago.