Many your choice should be based upon how you use your computer. Do you make videos? How large is your "My Documents" folder right now? Do you store a lot of pictures on your computer? Do any of your programs create caches in the user folder? Is AH your only game, or do you also have a large Steam library?
I like the SSD as a boot device, because it makes it easier to get back into AH if there is a reboot required after a disconnect. It is really nice to have the system up and running in very few seconds, but like Bizman said that doesn't really do much for you. However, I also run a few programs like 3DS Max that take forever to load from a hard drive. The SSD doesn't really change that, but it is faster.
Either way, if you are downloading videos a lot then you will want to store them on a hard drive rather than an SSD. SSDs are getting better, but it is still not a good idea to write a ton of data to one and then erase it often. So your libraries (My Documents, pictures, videos, and Downloads) should be moved to a hard drive. When you do that Windows 10 (if you use that) will reset those folders to the SSD, so every time there is an update you just move them back.
Photoshop, Premiere Pro, Media Encoder, etc. all create large cache files that are stored in your user folder. You can use the apps preferences to move those caches to a hard drive. It's not hard to do.
Boom! Lightning fast system that should last a long time. Just backup your OS to another hard drive and you're done and ready for rapid restore if you ever need to.