Renderware is more of a 3d game development environment/game engine. They provide libraries, etc. I know there is a Renderware level editing tool, but I don't know if they provide modelling software or not.
Maya is a pretty sweet package. Its animation capabilities are second to none, although IMHO its modelling tools aren't that great and neither is its default renderer (doesn't matter for games unless you're talking about producing CGI cutscenes). Max is a powerful piece of software, but Maya is equal or better in just about every way. Keep in mind that Max is used for a fair share of game development as well. It's every bit as much of a professional product as Maya or Softimage (although it may be less expensive). I don't have extensive experience with XSI, but I do believe it's targeted more towards high quality cinematic/commercial applications.
Last but not least, we have Lightwave 3D. This is a great program too, and you can kind of look at it as the reverse of Maya -- its modelling tools and interface are awesome, and it has a great built-in renderer, but its animation capabilities aren't up to scratch with what Maya offers (Lightwave can do most of the same things, but the interface for animating isn't as easy to use). Lightwave is used in a good number of games as well, and it's the package that I myself use. It's not unheard of for companies to use Lightwave for modelling and rendering, and Maya for doing the animation work -- in fact, I believe this was done with the CGI sequences for Microsoft's Age of Mythology. Lightwave's interface, unlike that of Maya or Max, is custom built, rather than being oriented around the Windows GUI. This gives it a better feel, IMHO. It's also a fair bit cheaper than any of the above mentioned products -- I recommend it if you're looking to get in to 3D (although keep in mind that there is an excellent open source package called Blender available as well).