As a pencil enthusiast, I love the rotring 600. I have two. I also loved rotring’s Tikky 1 (not the subsequent ones)

Other great pen/pencil:

- Pentel Ortez. I have the 3 mm and, if used properly, the lead wont break

- Zebra delguard. Also wont break. I have it in 0.5 mm

- Rotring’s artpen. My favorite fountain pen, but it appears discontinued :S