This discussion is geared towards providing tips from personal experiences as to what writing tools to use when getting baseballs signed. Almost all of the big autograph companies, such as Steiner, Tri Star, and Mounted Memories, use blue ballpoint pens exclusively in their signings. I know for a fact that Tri Star used to only use blue Bic Accountant pens for their signings, but Bic discontinued production of these pens (for some unknown reason). They still make them in black and red ink, I believe. So the pen of choice in the industry now is the Bic blue Roundstic grip ballpoint pen. A lot of other collectors I know also like to use the Bic Cristal ballpoint pen as well. The color you choose is ultimately up to you, but I always prefer blue.
Personally, I have become enamored with the Uniball Jetstream 1.0 blue rollerball pen. I've found that this has an ink with a nice blue hue similar to standard ballpoint pens, but it writes much bolder on baseballs. Plus, the ink is supposed to be smear and fade resistant, which is the major compaint I have with standard ballpoint pens (fading). I have has a couple of instances where the pen didnt write 100%, but I think it was more a function of the angle the athlete held the pen at when they signed more than anything else.
There are a lot of other collectors that like getting baseballs signed in Sharpie (fine and ultra fine point). I have heard from various collectors that autographs done in in Sharpie marker on baseballs will bleed or fade a lot more than ballpoint autographs over time. Personally, I have never witnessed this, but I'd like to hear from other collectors on this forum what your experiences have been. I have also heard of some people liking using the fine point Staedtler Lumocolor pen as well, although I have not tried using that on baseballs.
Anyway, please feel free to chime in with your own preferences and experiences getting baseballs signed. Thanks!