Congrats on making the switch

The little batteries are frustrating over time, but it's served you well. I'll always be grateful for my overpriced mall kit that helped me switch to vaping. If only I'd known about ECF. Have fun finding the right step-up for you. We all have opinions. Only yours matters. You've got a lot of good info to sort through. I'll add to your pile:
I'm not an e-Power fan (yet). The complaints are that a kit is only one unit and it's a new product offering with issues. I understand you can switch out batteries like a mod but you still only have one unit. Part of the fun of vaping is having several batteries loaded with different flavors. The 18650 e-Powers are having issues. Hoosier was selling his bare-bones e-Power model for $15 with a warning, no warranty because of problems. I suspect they'll get a lot better in future generations if the market demands. Being an early-adopter on these could be risky imo.
KGO is my first choice for a new or upgrading vaper because of higher voltage than eGo and Riva and two batteries rather than one e-Power in the kit and KGOs have been around a while. Mine have been working for 5-6 months and function like new. It's a better, harder hit (video below) and at 1100 mAh, a batt will last most vapers more than a day. FYI 100 mAh = aprox 1 hour of moderate vaping. A KGO batt should deliver around 11 hours of moderate vaping on a charge.
The KGOs have an elegant, sleek look and are not as fat as a Riva/eGo. The titanium and chrome models are very nice looking when you can find them in stock. $45 for a kit with 2 batts, charger etc.
Many here cheer for the Riva Lite Bundle at LF for $30. I do too when price is #1 factor and it's a vaper's first kit. I'd go the extra $15 for a higher voltage KGO with much higher mAh. KGOs vape like a mod with a Fat Batt price. I don't take my Silver Bullet or Omega mods out of the house because I'm female and they're large mods. I get as good a vape with a KGO and don't feel weird about it in public.
You won't make a huge error getting a Riva or eGo. They're good fat batt models also. KGO is a better unit imo.
ECF suppliers that sell KGOs
Hoosier E Cig Supply
BreezEsmokes click KGO on list on left
KGO video info
hoosierecigsupply.com 1100mAh eGo battery whips AW 18650 IMR - YouTube
K-GO : DUAL COIL CARTOMIZERS - YouTube