Titanium is the best client to use if you plan to play on servers like Project 1999 that don't support the newer clients, but most servers do support them. I would not recommend the SoF client, as it is a little unstable. Personally, my favorite client is the SoD one from Steam (or Underfoot if you can get the needed files to copy over for it). For servers that support them, the SoD client is really great. It has tons of extra features and supports far more content than Titanium does. Plus, SoD is more compatible with newer multi-core CPUs, which makes the setup easier if you have a multi-core CPU.
Some servers have SoD content available (like my server, Storm Haven), and without SoD, you will not be able to experience that content. You can still progress well enough on Titanium, but you will be missing out on a lot of cool content for SoF+ clients.
The getting started guide here has more information on the supported clients:
http://www.eqemulator.org/wiki/wikka...akka=PlayGuide
And you can click the View links on the server list page here for details on each server:
http://www.eqemulator.org/index.php?pageid=serverlist