I think metal pocket pens are my favourite style of pen.

From the top: Namisu Pocket Nova Titanium, Ensso Pocket Italia Titanium, Gravitas Pocket Titanium, Gravitas Pocket Aluminum, Fifty4T Pocket Titanium, Pilot Myu, and Ensso XS Minimalist Titanium. I think my favourites of the bunch are the Italia and the Myu... though that's not firm!