I use joyetech eGo-c almost exclusively. But I've had other brands and knockoffs in the past. I have a Spinner and some eGo-RS's that have the replaceable 14500 batts. Joyetechs the best short and charge protection available for ego style batts. They have a longer than most cutoff - 13-15 seconds vs. as short as 6-7 seconds on some Visions and knockoffs. In general I've found that Joye eGos have better threading, durability and if you have a 'bad connection' it is almost always the clearo or carto that needs the center pin to be raised rather than the Joye eGo. Not so on some other models. Over the 3 plus years I've used Joyes, I've had 2 (not eGo-c's) die of shorts and the rest from old age - anywhere from 7-8 months to over 2 years depending on how much they are used...ymmv. I don't power vape any of them splitting up vape time with different eGo's tied to different flavors I like, with a 'backup batt' for each.
I also like the white to light blue to dark blue to indicate how much charge is left and with the eGo-c 'upgrade' battery, I like the choice of the regulated or unregulated modes for times when I need just a bit more heat for some flavors.