Ballpoint pens. Bic, Papermate, and Zebra are pretty much all I would consider buying.
Edit: there are lots of other brands that I forgot to consider. I'm mainly talking about inexpensive plastic tubes, but included Zebra (a metal tube) which I'm a fan of.
Had a generic refill in one of my zebras and holy crap was that crap. I could not reliably get it to write off a cold start. And it was fresh, just constantly getting stuck.