Depends really on your current standing in terms of power and ninjas, you should look thru all super rare skills and see what you would like the most atm

Personally I recommend pulling for 3rd Raikage for newer players, or Han if you want to use the "cancer" teams to beat higher powers

Roshi is more of a power ninja, GNW super rares are great always but keep in mind that you do need 1000+ pulls for them