What works best for me is to tailor the device to what I am doing at the time.
The 510 is great for when you are on the go, but remember to bring an extra battery with you. It is small, and, in my opinion, the easiest to carry in your pocket.
The 901 is my favorite for around the house, like when I am cleaning or doing yard work. It has better battery life, but is larger, and tends to go through liquid faster for me.
The 801 is big and bulky, but it produces a CLOUD of vapor. I prefer this one with a USB passthrough, for when I am in front of the computer. Plus, if I am playing video games or watching TV, I plug the passthrough into my xbox USB port, using a USB extension, and nearly never ending vapor is the result.
Granted, I am talking about buying three different devices, but I have found that having several and using them for the jobs for which they are best suited is the best you can get.
The 510 is great for when you are on the go, but remember to bring an extra battery with you. It is small, and, in my opinion, the easiest to carry in your pocket.
The 901 is my favorite for around the house, like when I am cleaning or doing yard work. It has better battery life, but is larger, and tends to go through liquid faster for me.
The 801 is big and bulky, but it produces a CLOUD of vapor. I prefer this one with a USB passthrough, for when I am in front of the computer. Plus, if I am playing video games or watching TV, I plug the passthrough into my xbox USB port, using a USB extension, and nearly never ending vapor is the result.
Granted, I am talking about buying three different devices, but I have found that having several and using them for the jobs for which they are best suited is the best you can get.