The problem is not, who knows their bible better, it's "who understands the others reasoning" better.
Witnesses are very GOOD at "disproving" things which others believe, whilst in reality they are disproving a "Straw Man" arguement.
Christians are very BAD at realising that is what the Witness has just done.
In effect both parties are arguing over different issues but don't realise it. As to who wins. . . neither or both!!