I have two box mods, Riva bats, and eGo USB bats. Lately I've been using the eGo the most.
It really just boils down to your personal preference. Box mod can fit entirely in your hand and is good for stealth vaping, and the on/off switch is great. The problem I had with one of my box mods was I dropped it and the little plastic latch that holds the battery compartment closed broke off, so now it doesn't stay closed. The eGo USB battery I like because I can use it as a passthrough on my computer, then just disconnect the mini-USB cable and screw the top back on, and I have a fully charged eGo battery to take with me when I'm out. Never have to worry about juggling uncharged bats.
Also, word of advice...be very careful not to overtighten cartomizers when using madvapes' 510->901/808-D adapter. You can also adjust the height of the connector with a small screwdriver for better airflow, there's a youtube video on here for it.
It really just boils down to your personal preference. Box mod can fit entirely in your hand and is good for stealth vaping, and the on/off switch is great. The problem I had with one of my box mods was I dropped it and the little plastic latch that holds the battery compartment closed broke off, so now it doesn't stay closed. The eGo USB battery I like because I can use it as a passthrough on my computer, then just disconnect the mini-USB cable and screw the top back on, and I have a fully charged eGo battery to take with me when I'm out. Never have to worry about juggling uncharged bats.
Also, word of advice...be very careful not to overtighten cartomizers when using madvapes' 510->901/808-D adapter. You can also adjust the height of the connector with a small screwdriver for better airflow, there's a youtube video on here for it.