I also first started with the Ego-C and it was enough to show me that vaping would work for me, BUT those darn leaking tanks.... lol gggrrrr.
They're good for that, a nice introduction to vaping and getting people through the initial quitting phase with enough of a quality vape to get people hooked.
Some continue to use them as their main and only vape, but the large majority graduate from our starter kits (whatever they may be) and move on to bigger and better setups.
I sometimes still use the Ego-C setup on my Provari. After messing with other setups and getting a better idea about wicking and atomizer care, I have none of the usual beginner issues that the Ego-C's have been blamed for. With the power of the Provari, and the juice leaving the tank right onto the atomizer, it makes some of the best vapes I've ever had. Great for tasting juices.
Though now I mainly use cartos with and without tanks and am soon to be the proud owner of a ScubaGen Mini V3 rebuildable atty / tank system. Which will more than likely become my main vape.
While real adjustable power can make for a big difference in vape quality, for the average beginning vaper just starting out with the battery locked in, 0.3v or 1w isn't really going to make any real noticable difference. Now if one of these batteries let you switch between the two voltages, I'd lean in it's favor just for giving the option.
The E-Power's batteries also cost much less than the ego's ($4 vs $15)]
This is another apples to oranges comparison that keeps getting repeated ad nauseam.
For "$4" (though I've not seen them that low, I've seen them for $6 at some "less than reputable" vendors) you're getting just a battery. I want to see someone take this battery and a filled carto, and get a vape off of it. Personally I think I'd be afraid to put a $4 battery in my PV but some are more adventurous than I. Most often I see them in the $8-10 range from reputable dealers.
For $15 (or less) you're getting basically a full PV with a finished case, a 510 connector, a battery, safety / protection circuitry, and a control switch. Add a filled carto and you're good to go.
So it's hardly a fair comparison.
It may be something to consider for upkeep and maintenance costs down the road if you don't plan on ever upgrading your setup, but for those just getting started vaper looking for a
starter kit, it can be pretty misleading.
Most of us would likely have moved on to other setups long before either the 18650 or Ego / Kgo battery died anyway.