Definately Kakashi. Guy may be strong but if 당신 think about their stregths a weaknesses kakashi's at a whole different level. Guy only can do taijutsu and has good Speed, strength and stamina. Whilst 카카시 선생님 can do Ninjutsu, Taijutsu and Genjutsu. and has good speed, intellegence, strength and hand signs. Also 카카시 선생님 has 더 많이 experience. 카카시 선생님 graduated academy at 5, chunin at 6 and jounin at 13 but guy academy at 7, chunin 11 and jounin in 20s.
BTW if 당신 can't read what says below here;
The eternal rivalry between Maito Gai and Hatake 카카시 선생님 is legendary, and they both prophesied they would one 일 do battle. Both Jounin's of awesome power, in their confrontation entry 옮기기 would be critical mind ful of this, 카카시 선생님 unleashes the power of his sharingan, to predict Gai's every move.