[Lookin4theBestNU]

On the other hand, other theories like Keirsey’s, believes that total opposites do attract, therefore the best partner for ESTP would be the reversal of their functions (INFJ).


Not exactly 'total'. Keirsey theory is that opposites attract except in Sensing and Intuition. He describes early on in the book that if people are opposite in this department it will be "like two strangers in a strange land". Theoretically (according to Keirsey) the ISFJ/ESTP or ISTJ/ESFP would be ideally matched. He goes on throughout the book in the relationship sections to describe how SJ/SP couples are suited so well and will share commonality in communication. The artisan/guardian pairings seem natural in his view. I do want to point out as well that he states that any two types can make a relationship work which I certainly believe! MBTIc doesn't have many ESTPs so it may take awhile to get a specific response on their view of ISTJs. I hope you get one though!