It depends on all the gear you're using and the INT difference but usually its MAB +2.5 > INT +1. Sometimes it can be as low as MAB +2 > INT +1 but it depends on the rest of your gear.
Using this formula which I've found to give almost exact numbers:
[(yourINT-targetINT)+25]*Staff*Day/Weather*(yourMAB/targetMDB)*Damage Adjustment*Ebullience
Lets say your gear is this(typical for a 75 SCH without endgame):
NQ Elemental Staves
Bugard Strap + 1: INT +1
Phantom Thalum: INT +2
Af Hat: INT +5
Elemental Torque
Moldivite Earring: MAB +5
Cunning Earring: INT +1
Errant Body: INT +10
Yigit Hands: INT +5 MAB +2
Snow Ring x2: INT +10
Rainbow Cape: INT +3
Penitent's Rope: INT +5
Errant Slops: INT +7
Yigit Feet: INT+3 MAB +2
Cream Puff: INT +7
Total: INT +58 MAB +9
I don't know a taru's base INT at 75 as SCH/RDM but this
site says 77 so I'll use that.
And lets pick Puddings because well they are the most common thing to nuke, they have INT 89.
Only Weather bonus will be used.
[(135-89)+25] * 1.1 * 1.1 * 1.29 * 1.25 * 1.2 = f166
Lets swap Moldivite for a Morion +1 so it will be MAB +5 vs. INT +2
[(137-89)+25] * 1.1 * 1.1 * 1.24 * 1.25 * 1.2 = f164
So a difference of 2 points of damage, now lets use MAB +4 instead of the Moldivite.
[(135-89)+25] * 1.1 * 1.1 * 1.28 * 1.25 * 1.2 = f164
So using the gear mentioned against Puddings it takes MAB +2.5 to beat INT +1.
Now lets use your gear choices that you mentioned.
Goliard vs. Yigit Feet:
[(136-89)+25] * 1.1 * 1.1 * 1.27 * 1.25 * 1.2 = f165
Yigit wins by 1 point of damage.
Prudence vs. Uggy:
Prudence: [(140-89)+25] * 1.1 * 1.1 * 1.29 * 1.25 * 1.2 = f177
Uggy: [(135-89)+25] * 1.1 * 1.1 * 1.37 * 1.25 * 1.2 = f176
Prudence wins by 1 point of damage.