It's quite OBVIOUS what the underperforming advisors need.
Lucky Lookout Leucon - Despite being named LUCKY, he doesn't boost critical strike damage nor critical chances for his scouts! Just let him add crit chances to buildings and scouts!
Odysseus - Barracks, Castellums, Archery Ranges, Auxilia Camps, and Siege Workshops cost 15% less and build 15% faster OR
Odysseus - Barracks and Castellums cost 15% less, build 15% faster, and work 10% harder (athenian training manual applied for free)
Rockhound Erastos - Villagers gather Stone 25% faster, Chisel, Stone Saw, and Stone Splitting are granted for free (even if the civ doesn't have access to it). Stone trickle at a rate of 0.4/0.6/0.8/1 per second.
Prince Niall Muighmedon - Storehouses and Ox Carts cost 45%/55%/65%/75% less and build in 20%/30%/40%/50% less time. Storehouse upgrades research in 50%/60%/70%/80% less time.
Closet Organizer Irene - Storehouse and workboat upgrades cost 45%/55%/65%/75% less.
Fisherman Finnbar - Fishing Boats cost 50% less, gather 20% faster and have 25% conservation. Allows Net Weights and Net Landline to be researched.
Grand Magistrate Diviciacus - Sacred Groves cost 50% less and spawn a free Sacred Deer every 30/25/20/15 seconds. Cooldown of Rites reduced by 10%/15%/20%/25%.