I blue use Paper Mate Inkjoy pens exclusively. They are cheap and reliable. I always have one in my pocket, and several at home, and it's no big deal to lend or give them away if someone is in need.
I once paid some $25 or so for a cheap aluminum "tactical pen", which I promptly gave away. Such a pain always having to twist the cap off, and it didn't write very well at all compared to the pens PMs. Also, it had a carbide breaker which could be unthreaded from inside the pen to be used on the butt, and it always unthreaded itself while I walked, causing rattle in my pocket. Soooooo annoying! I carry pens to write with, not to take out sentries and body guards. So Paper Mate it is.