The newest Epower switches work great with no issues, it was only the old switches that had problems, yet people still seem to use that as their reasoning to not get an Epower.
I've had an Epower for about 9 months and have never had a switch fail. I still even have the original switch that came with my Epower and it works fine, yet I don't really use it anymore bc I bought the newest one bc I wanted the 5-click on/off feature.
Personally I'd say go with the Epower. You can buy 4 Epower batteries for the cost of 1 kGo battery, and they last longer before they need to be replaced. With the Epower having replaceable parts, it is a lot cheaper to maintain bc you dont have to replace the entire unit Everytime any part goes bad. Also, I personally think its a lot easier to carry a spare battery for the Epower than to carry a spare battery for a kGo. With the kGo, if you want to carry a spare battery, or even 2 spare batteries bc your going to be away for awhile , you have no choice but to carry 2 PVs with you, or 3 PVs if you want 2 spares. (who has the pocket space to carry 3 PVs?). With the Epower though, you only have to carry one PV and the batteries are small so it's very easy to throw an extra or 2 in your pocket and If needed unscrew the switch and pop in a fresh battery. (Having to carry numerous kGos just so you can have a spare battery might not bother some people, but personally I think that's a PITA. Everyone's different so it's something to consider)
With the Epower batteries being so cheap, it's easy and won't break the bank to just buy 4-5 and never have to worry about not having a charged battery. I went on a camping trip with a buddy awhile back for a few days. He uses a kGo while I had an Epower. We both decided to buy 4 batteries to bring so we'd be good for the whole trip since there wouldn't be any outlets to charge. We ordered them together from a vendor that sold both to save on shipping. My buddy had to drop $72 + half the shipping cost to get 4 kGo spare batteries, while my 4 Epower batteries cost only $16 + half the shipping cost. I also ended up ordering a bunch of cartos to take also since my 4 Epower batts cost $2 less than the cost of one of his $18 kGo batteries.
I'm not saying that the kGo is a bad PV bc it's not at all and I honestly think you'd be really happy with either one, I just want you to see the pluses and minuses of both sides.
I can almost guarantee that the majority of the kGo users in this thread that recommended you get the kGo and talked trash on the Epower have never used or even touched an Epower. A lot of kGo users use the "the switch is problematic" statement as their reason you shouldn't get an Epower, but in reality most kGo users only say that bc they heard someone else say it about The first generation switches, which by the way did have problems. The newest switches work awesome though and are not problematic like the old switches from when the Epower first came out were. People say the Epower switches are so bad, but The kGo switches can at times be problematic too. One of my other friends that has a kGo has had to replace 2 batteries bc the switches had problems and stopped working, and he's also had the rubber button fall out of the device more than once.
Like I said, I really think you'd be happy with either one, just make sure you look at the positive and negatives of both devices and pick the one that you feel fits you best.
Goodluck!