Lewandowski managed to outscore him with 22 goals in 27 fewer matches, Müller who’s not even a striker is pretty much equal with him as you said 
https://en.m.wikipedia.org/wiki/List_of_UEFA_Champions_League_top_scorers
Zlatan is a great player no doubt, but he was relative poor in the CL. Funny no journalists never dared asking him about it

https://en.m.wikipedia.org/wiki/List_of_UEFA_Champions_League_top_scorers
Zlatan is a great player no doubt, but he was relative poor in the CL. Funny no journalists never dared asking him about it
Zlatan on the other hand will always be remembered as special and will have a following. Because of his character, his unique goals, because he keeps going strong at 39 like nobody else in football's history, because his own teammates shit their pants when he's on the pitch and they will talk about him until they die, because "no journalists dared to ask him why he wasn't successful in CL" as you said.
So yes, if we're talking about a 3rd player that marked the last decade or 15 years, it's Zlatan.
