I'm drawn to SPs because of their often light-hearted, fun-loving ways. I live for fun, I detest emotional drama (personal emotional drama is fine, seeking to understand one's self is great, it's when the drama involves multiple people that I turn off), and I enjoy their action-seeking preference.
Many of my closest friends over the years have been ESTP specifically, but all SPs are represented.
I found the SP friendships that meant the most to me were satisfying because they never asked/needed/wanted me to change but at the same time challenged me to be more action-orientated. It doesn't take too much encouragement but I will withdraw without some.
The more satisfying SP relationships were ones where I never asked them to bare their souls, and they never asked me to either, and yet we understood each other enough to challenge aspects that needed to be pushed and avoid areas that were touchy.
If I came up with a crazy plan they jumped right in to help with the plot, they never looked at me like I was odd. They encouraged the crazy.
They were fun. They were drama free. They were super enthusiastic. They liked people. They were optimistic. They were positive. The relationships were symbiotic.
That for me is satisfying.
With INFJs there is still the element of encouragement (although they can look at me like I'm odd

), but the most satisfying aspect of my relationships there is the depth that we are able to get out of each other.
When they are receptive I know how to open them up, and they are the only type I've found that is able to turn that back on me and get me to reveal things I normally keep well hidden. They refuse to allow me not to.
We get each other, but both sides of the relationship are looking for continual improvement and growth, we never stop challenging each other to become better people.
I find it impossible not to admire many innate INFJ traits when I see them in action.