I'd place the two as practically even, so Janemba's far better and less predictable techniques give him the win. Pan's stamina doesn't seem to be too great, considering the heat of a desert planet throughout what seemed to be a few hours dehydrated her enough be overpowered by some arthropods even Gill could fend off, which is very unimpressive when considering far earlier feats such as 22nd TB Goku travelling halfway across the world without rest or Namek vegeta fighting for nearly 6 days straight, so Janemba could definitely win a war of attrition if it comes to that.