Yes Aguero is better than Mbappe, and it is not even remotely close. I am talking career wise, peak Aguero was right up there with the very best to play the game. I mean you are looking at one of the best strikers ever in the prem. When it is all said and done and Aguero hangs up his boots he will be talked about alongside Henry.
Of course Pep would swap Aguero for Mbappe, you are talking about a striker who is coming to the end of his career at the top level versus a striker who could potentially lead the line for the next 10 years. But Aguero has done that, he has been that elite level striker. Mbappe, has the potential no doubt, and clubs will pay top dollar for a young striker with his kind of ceiling.
Kane is in his prime, and whats his knockout record got to do with anything? He plays for an average team, full of mostly average players, except for Son, that guy is a beast. Has had some injuries the last two seasons but has still posted respectable totals. He certainly isnt flashy, but the stats speak for themselves in regards to Kane. Going just on his goals to games return he is a shade under Aguero and Henry, with clear daylight to the chasing pack of Shearer and co. Fastest player ever to 20 CL goals, you have to go back some way to find a striker with his sort of goals to games ratio for England.
Mbappe last season was amazing, but one great season does not a world class striker make. He certainly has the potential to go all the way, and I think he is in a good spot at PSG, plenty of game time, CL football. Can always move to Barca, RM, Bayern, one of the giants of world football later in his career.