So just a fun post what I believe they take the respective stat in 

Haki -garp . He only uses his fist so logically his haki should be greater especially the armament 

Endurance -whitebeard . Look at their old age damage difference 

https://preview.redd.it/prime-roger-and-garp-vs-prime-rocks-and-prime-whitebeard-v0-g12cgyyluw0g1.jpeg?width=1859&format=pjpg&auto=webp&s=931cde801e287a4239332572a5acac035760c0e5

Durability -equal . Id say they have no durability feat that puts the other above the latter . Garp could maybe be argued as more durable due to his superior armament . 

Speed -garp . Going off their old selves again her for scaling , oldbeard was kinda slow even if it was due to his age . Whilst old garp outpaced kuzan on several occasions . 

Physical prowess - whitebeard . I believe due to whitebeards stature and the feats he has shown he gotta edge Garp out slightly , Garp is a normal human whilst whitebeard could very well be a buccaneer.

 Ap - Whitebeard . Having a supreme grade blade plus a devil fruit edges Garp out imo . Cutting attacks are more deadly than blunt force most of the time in the story 

Dc- whitbeards . Power to destroy the world tremors etc no debate here 

 Battle iq -equal .same here nothing seen to put either above the other from my knowledge 

Iq -equal . Haven’t seen anything that puts either above the former 

Practice of their respective craft -garp . He earned his fists by hitting battleships like brannew mentioned . He is also the best h2h fighter in the old gen , being able to fight monsters that wield supreme graded blades with his bare fists 

So in conclusion I believe primebeard in a fight edges out prime garp . 

Old selves garp mops the floor with oldbeard due to sickness n better feats ( part from endurance ) 

Primebeard / garp stats comparison ( vibe scaling )