I've always been annoyed at how terrible the vanilla entity model code is, how terrible the entity model code you get from 3rd party modeling tools is, how limited the features are, and how your models could be rendered unusable by a minecraft update. So, I fixed the problem myself.
Introducing Minecraft Model Studio: an all-in-one modeler, poser, and animator (better texture editing support coming eventually).
The program running. This is a machine from my WIP mod - as you can see, I am even able to place item render spots into the model!
Why should I use this?
because, to put it simply, it's just better than the trash you've been using. All models are saved into a combination of OBJ mesh files and XML skeleton/effect files. Just copy the API classes into your mod source (API available for forge 1.8.9, 1.9.4, 1.10.2, 1.11.2, 1.12.2, 1.13.2, and 1.14.4. 1.15 and 1.16 will take some more time, sorry!), use the built-in code to manage the loading and rendering of models, and you're done. No annoying code imports or worrying about updates breaking your models. Also, animations can be played simultaneously - if an animation is marked as relative, it will apply it's transforms on top of previous poses (from the base model and animations) - use it to make knockback effects, inverse kinematics, whatever! It's up to you!
How do I use this? Unfortunately, I do not yet have a usage guide. For now, you can head on over to the discord https://discord.gg/3ESEY6j and ask for help there. The program is fairly easy to learn.
I made a video tutorial! Great! give me a link and I'll check it out - if it's good, I may put it here for all to see!
I used this in my mod, will you shout it out? Unfortunately, I cannot. If I shout yours out, I have to shout out everyone's, and that may or may not end up being a lot of mods. If your mod utilizes the features in creative ways, I may still shout it out though!