So far I haven’t really been happy with any pen…
The shape that all vendors seem to have adopted as standard with minor variations now feels too fat to me too.
But I still have a super old stylus from an Intuos before they had numbers (and USB 
), but that one is too slim, and it’s also very top-heavy, so I wouldn’t want to use that one either.
Unfortunately no vendor specifies the diameter of their pens, and there is no store here were you could just give them a try, but I’d be curious how the Wacom “Pro Pen slim” feels (though given the steep price, it sucks you can’t just pick your preferred pen when buying a new tablet)