I like Zebra and Pentel gel ink pens. 0.5-1.0 mm sizes. 1.0mm is for signing documents and at the cashiers.

I also use these "pens" very often: https://www.amazon.com/Tungsten-Carbide-Engraver-Stainless-Ceramics/dp/B0819GJWX3/ref=mp_s_a_1_1?dchild=1&keywords=Tungsten+scribe+pen&qid=1634691253&sr=8-1

I always carry at least one pen, one scriber, USB flash stick, and a small knife on my lanyard.