Uh higher level = higher exp, don't really need a list. Highest i remember are the level 75 guys in maps near sand village, and they are very easy, can kill them at level 40-50~ maybe, i remember trying for fun.

But really you don't need them, if you swap your ninjas our during sweeps you can get sooo much free exp, later levels give like 80-120k exp per sweep. All my ninjas are same level as main and i still have thousands of food items left.

its worthless to bother trying to do those, sweeps give tons more exp and on mondays its doubled so 240k exp per sweep at lvl 70+

240k*44 = 10,560k exp on monday from free stam alone more if u save up from sunday and use pots

lvl 85 is 2.4mil for cap of non main ninjas which means lvl 81 to 85 in 1 monday