I would recommend understanding the requirements of the 3D modeling and rendering programs. These can usually be found on the sites for each piece of software. Keep in mind they are telling you a minimum, but that can always change as they update the program - which means they can actually require more.
The nice thing about a tower machine is you can upgrade components as you go. An SSD for your boot disk would be faster than a regular HDD and allows for fast read/write and boot up. The separate HDD storage is a good option as well. Depending on the software and file sizes you use it can gobble up that space - but its upgradeable.
Consider these factors and how long the tech has been on the market, it could become outdated fairly quickly since the tech cycle is about 2-4 years depending. So bang for buck might be there, but consider investing in something you can use in 2-4 years and keep up. Gaming PCs are some of the more rigorous setups, but they also would exceed many of the parameters and requirements of what you would be using software wise.