This
Thinkpad digitizer pen works well. It has both a button and an eraser, and the one that I got years ago came with a "flex" nib (see this
article on Wacom nibs).
However, the stylus that shipped with my Max 2 seems better at creating varying line widths by tilting the pen.
The HP Zbook X2 pen also is fully functional (with eraser). Mine came in a package with a nice case, nib remover, 4 spare plastic nibs, and 6 fiber nibs.
FYI, the approximate diameters of the nibs on these pens is as follows:
Max 2 nib 1.54 mm (tip), 0.84 mm (shaft)
Thinkpad nib 1.30 mm
Zbook X2 nib 1.52 mm (tip), 0.95 mm (shaft)