Despite my moving away from Cinema 4D more and more, I still follow it with some interest and so inside myself I’m still torn. Part of that is of course X-Particles. While I’ve never used it much for serious stuff, it’s one of those truly unique plug-ins that gets you hooked and then you find yourself idling away an afternoon watching it do its thing and creating those weird, but beautiful structures from its connected particles or some cool looking other stuff. Now with version 3 they have upped the ante again and introduced a grid/FLIP solver for smoke, fire and even better liquids so it goes without saying that you probably won’t be able to evade this as an “essential” plug-in and just buy it. It does so much and the pricing is still extremely reasonable. Check out their stuff on their web site.