Depend on your goal and situation, you want a faster sage team to guarantee top 3 spot then go for Hiruzen. But if you want to fight people around your power level then pick cool tobi.

PvP wise, hiruzen can beat cool tobi if you stack your hiruzen enough. However the jonin minato - cool tobi duo are also very strong in 1v1 pvp as long as you have higher ini than your opponent,