That's politics babe.. You don't judge who you trust but judge who you can gain more(⌒▽⌒)
In instances you don't side with any of them. You secretly raise power and become a shadow king by instilling a mentally weak royal or you incite a rebellion and instill a new goverment.
Or, you quietly make your wealth and then fuck off to the countryside so the cycle of kingkillers becoming kings can continue without adding you to the death tally. All you can trust is that inevitably you will die. The only question is when
Spoiler
Suggestions don't side with any of them they are bound to end .
With the princes I don’t know which one of them to really side with they both seem very untrustworthy