Depends on the game. If it's something i'm more used to, I start with the default settings. If it's something new for me or needs many different button pressings (I've grown rather slow with those), I'll take easy.

Keep in mind the space management games that I prefer to play, like Rimworld, Rise to Ruins or Oxygen Not Included are pretty difficult already to begin with.

I used to be a pussy about difficulty. If there was an easy option, I would take it because I thought that if the devs are offering that option, why should I needlessly make things more difficult for myself. But that was way back when I was younger.
Nowadays I always pick Normal difficulty, because that's supposed to represent the game as it was intended to be experienced.

Always normal.

Whatever the Standard/Normal setting is.

Depends on the game. If there's an achievement for hard mode then I will play hard mode, otherwise its on normal. If the game I know is easy on normal then I bump it to hard like doom eternal, assasin creed odyssey and vahalla and so on. Any dark souks like game is played on normal ?

Typically on hard (especially if there is a level above that), sometimes I do normal though.

Hardest one available.

I typically leave it on the default difficulty, or up it to a harder setting if the default setting is too easy. I turn on hardcore mode for most RPGs, for example, I always play Fire Emblem games with permadeath on.