A wins this one......
A in lightning armour goes toe to toe with Minato's speed and currently the fastest ninja alive having chakra upto bijuu lvl and possibly the strongest in physical strength, too...
B on the other hand is good as hell,too. Perfect jinchuriki and user of TBB...
BUT A trained B and were considered strongest duo,so anyone who thinks B can easily overwhelm A are just small kids who just watch Naruto as moving pictures bcoz every time B tries to put someone above his lvl, he always compares it with A, a confirmation statement that B knows A is stronger AND A has no problem with B's transformations, it has been said that A had fought Hachibi head to head and even severed it's one of the horns and V.2 is just a humanoid form of Hachibi condensing all the power into a small structure increasing the strength and speed of B which can slightly be compared to A's speed at lvl.2 armour and also A has been proven to be a beyond limits durable, he stood calmly even his hand burned out with amaterasu and when B defeated A with lariat A was just pushed backward on the other hand we know the other results of B's lariat against Sasuke and Kisame....
In the last TBB is a child's play for someone fast like A and A is just superior in taijutsu than B, it's a fact.....Samehada is a real deal but again A's single full speed punch is enough to take samehada out of the battle.....
Note: those who think A's lariat being inferior to B's make B stronger than A are dumbs, A just don't use lariat as his sign. move coz he has hell lot of better moves than it......