I had a similar dilemma, but between Kane and Son. Son stepped up at a vital time, despite his World Cup exploits, the turmoil of failing there and then two more international tournaments, but if we really weigh it up rationally, Kane has still contributed more to our season than Son. And if we include Kane or Son, then we still have to consider Eriksen. For all the lull in pizzazz lately, he's still influenced us being in the top 4 massively over the course of the season, our third most productive player in terms of raw goals/assists, he's now being asked to do a completely different role for much of this season, helping to hold a midfield together as well as being expected to still create and score, I think if you were to objectively quantify it - ie who scores/assists, who sees the ball the most, who covers more ground - Eriksen would probably top that collective algorithm. Then you factor in that nobody in our team provides the intelligence he does, hard to quantify or qualify, we are not the same team when he is not there. Alli brings some of that, as does Kane but nowhere near the same influence.
It's a toughie.