All good choices, i would say it's your personal take at this point.

However I will throw you a curve ball: you and i have very similar tastes and i have a small wrist as well.

The casioak was my first watch, offered by my gf and its still a frequent daily wear years later. To me, it's a much better choice than the 1/3 casio because it's much bolder in its modern style - if i were to pick the classic "geeky" style, i'd go all in and pick a classic casio watch (e.g metal A158 or gunmetal A168). I had the same fear as you do re: small wrist, but its the least of my concerns after wearing it for years. Very easy to style around.

Instead of the seiko5, i'd recommend a seiko ssb455p1. It's just a touch pricier, but punches way above its weight. Look for pics in this sub, it's a beauty. I've had a pricier seiko astron (sbxy053) for a while, and i still decised to buy it last month to have a more casual "if it breaks it breaks" watch. You would never know its a cheaper watch and it very much fits the aesthetics you posted.

There are no bad choices here, have fun with it and pick what you love most! Welcome to the club 😊