I mostly use a Provari now, but I used 1300 mah Vision Spinners for quite a while, and I was pretty happy with them. I still have a couple as backups. I think the choice between Joytech eGo's and Vision Spinners is just personal preference. I liked the size of the Spinners. The 1000 mah eGo's were longer, thinner, for less mah, and I liked the Spinners better, but that's just my choice. They give essentially the same results.
IMO, you don't need to know the actual voltage your using. Turn it up, or turn it down, as needed, until it gives you the results you want. Too high will start giving a burned taste, too low gives you far less flavor and vapor. That's the whole point of variable voltage, to be able to adjust to get it just right. The numbers don't really matter.