"People who have completed this game 100+ times, tell me in a few words, which starting option is best and why? The character, their story, and location... For example, I heard if you choose the CASTLE, you can find your mother have a brothel, but if you choose the farm, she works brothel in the village... Basically, explain it in that sense. I just haven't noticed much talk about the Templar (or whatever he's called), Thief, or Mage Guild."
Basically, Farm and Noble origins have the most content by far. Most of this does involve the MC's family, so decide for yourself.
There are basically 3 brothels in the game:
1. In Summeredge (capital city) is a high end club, owned by Noble MC's mother.
2. A small tavern in Slinsk (port town) where Farm MC's mother works.
3. You have the option to establish one in your own castle where various female NPCs and companions can work.
Everyone gets access to the club in Summeredge, Noble MC just gets more content for it.
However the tavern in 2. is exclusive for Farm origin and FMC can also work there.
You get the castle regardless of your origin, that will be your base and you have most of your interactions with your companions there.
Every origin has some unique scenes, Farm and Noble simply have significantly more. Mage origin is relatively new, so it was not discussed as much yet and Templar got a few updates later on and it kind of took the third place in popularity, based on what i've seen. Soldier and Thief are not bad, they just never got the same attention from the devs and so they are not as popular.