id say naruto is the best because he has the harder job of balancing his chakra, the fox's when going in sage mode.
Hasihrama can go instantly in it and seems very good at it.
Kabuto needed orocihmaru's dna so hes not that good.
Jiraiya needed Ma and Pa frog to aid him. Jiraiya didn't have any special add ons like kabuto , so its easy why jiraiya had to do it the hard way.
But each sage mode is different,
Toad sage mode requires to stay still to continue getting natural energy. The other sage modes seem to not worry about this concern but Toad sage mode offers big advantages compared to the others as a result.
1) it boosts all ninjutsu(including genjutsu) and pyscial body(taijutsu)
2) Increases reach with Frog fu
3) gives sensing abilities when mastered a level on their own. To the point it helps you dodge in fights real time.