I like this mod for the DNA chip that it houses. It's capable of going to 75watts and it can hold 2 18650 batteries. This should be enough power to chain vape a whole day at 75watts.
Round 6 Entry 1 Original HCigar VT75 TC Box Mod - TIFFANY BLUE
Still my favorite out of all that's offered on GearBest.com (and there are top-notch items to choose from), I love the Tiffany Bluecolor, 75w (plenty of power for me), replaceable 18650 or 26650 battery, and that awesome DNA75 chip that allows the fun of customizing with Escribe software,
Original Hcigar VT75 NANO Box Mod - RED
Almost like my first choice, the full-size HCigar VT75, except for the smaller size and you only have the option of using an 18650 battery to power it. Also, it lists the option of "Customized LED Fire Light". Otherwise, like the larger version, I love the color, 75 watts of power and the DNA75 chip. This mod will work well as a take-along device since it's small but powerful.
Round 6 Entry 2 http://www.gearbest.com/clearomizers/pp_425056.html?wid=21
Tried this tank one day on a friends device, and was blown away by the quality of the vape it provides. I had sworn off premade coils long ago, but this quickly changed my mind. The flavor and cloud production is unmatched, and coupled with the quality that Smok provides in their tanks it is a winner for sure. With the addition of my newborn to my family, I have been back in the market for a tank like this to eliminate some of the maintenance my RDAs require.