[CCIP]

My own preference would be SHIV - doesn't have some of the bells and whistles of the more advanced SHIII mods, but it's solid, the major mods (whether you like playing Americans or Germans) are simple to install and rock solid, the game looks and performs much better than SHIII (much shorter loading times, much better graphics, much simpler to configure), crew management is much better implemented, and honestly if you choose RFB, TMO or OM mods - you get something that's pretty darn complete and good to play. It has the largest number of available subs to play, and the game's file structure has made it very easy to add playable ships if you feel like taking some big guns out for a whirl. I disagree with Steve that it's been 'ignored' by modders by the way - that's far from true and the amount of modding in SHIV can definitely stand up to the other two games, and much exceeds what's currently there in SH5 (but that's because it's been out longer). Still lots of good things being made for it.

It seems to be the most overlooked of the three, whereas I personally think it's the most solid. Again, SHIII has had an additional 2 years of modding development and it shows, but it's also a much older platform. And if you're starting out, you might not even appreciate all the bells and whistles immediately, but you will probably appreciate the ease of install, nicer graphics and performance (compared to SH3), and relative lack of major problems (compared to SH5).