The question of "What 3D program to go with for the purpose of making images and videos" is, first and foremost, one of "how much time are you willing to put in." On one hand, Source Filmmaker has a lot of assets which you can use, many close to hand via the workshop, and is simple enough that you can make renders (pictures) after an afternoon of tutorial. On the other, Blender lets you do all the same stuff *and* lets make your own assets, from the model to the texture to the maps to the animation rig to the skybox, but getting to any level beyond "posing models taken off of other websites" takes days of tutorials and weeks of practice.
I would recommend the latter option. As someone who's seen a lot of 3D porn and made a little himself, here's the thing: it's basically photography where you personally sculpt every aspect of the set. Most people forget that lighting and composition and colors all still matter, though, and that's why you can find an unlimited number of extremely low-effort renders of whatever you could possibly imagine. If you just get a bunch of high-quality assets and don't pay attention to the style consistency or the direction or the shot itself besides a vague idea, it will look like garbage and be artistic shovelware that nobody comes back to a second time. Once you get good, though, you can make anything you want, and once you get really good, you can make anything you want and have it look just like real life. Finally, having to go through all those tutorials will encourage you to go through a few more to do it right, and I will tell you, most good renders and animations are made in Blender/Maya not because they are inherently better tools but because the longer learning process makes it less likely that some lazyboner will do the bare minimum to put out crap and then keep doing that forever.
Plus, the Blender experience will translate easier into real jobs and more respectable creations, should you wish to go that route.