Thats awesome that Della did that!
It seems that you like LR attys/cartos and will prob be using them alot. If you are, I would def go with a 3.7V PV over the eGo. You can fry an eGo battery using 1.5ohm or 1.7ohm cartos. Even the 2.0ohm stress the battery slightly, but theres a lot less of a chance of frying the mosfet with the 2.0ohms. A 3.7V will give a slightly warmer vape and slightly more TH than an eGo, and the 3.7Vs also handle LR attys/cartos much better. The Riva, kGo, and E-Power are all nice 3.7V that are fairly inexpensive. I use an E-Power and love it. The E-Power is very similar to the Riva/kGo, but is the only one out of the 3 that uses non-proprietary batteries and thats what I really liked. E-Power batteries cost $4 compared to eGo/Riva/kGo batteries that are $14-20, and they last a lot longer before they need to be replaced. What I also like with the batteries is that its very easy to carry a spare. E-Power batteries are about the size of a AA, but alittle longer, so its very easy to throw an extra in your pocket. They are 1050mah and you get 2 with the kit, I get about a day to a day and a half on one battery. Also everything is replaceable on the E-Power so it really keeps costs down, which I really liked. The kGo and Riva are both really nice but thats one thing I dont like about them. The tube, battery, and switch are all one piece. So if your switch fails, you have to buy a whole new unit. If your battery fails, whole new unit. On the E-Power the battery, tube, and switch are all seperate. So if you need a new switch, you can buy just a new switch and keep using your existing tube and battery.
I also dont like that since the eGo/Riva/kGo do have proprietary batteries, if you want to carry a spare battery, you basically have to carry 2 PVs. Which isnt horrible, but when your out all day and always going to places for work like I am, carrying a backup would be kind of annoying.
The Riva and kGo are both great PVs, the E-Power just fit my needs better. But both are popular and work very well. Id prob pick the kGo over the Riva bc it has a 1100mah battery and most lGo users get at least a day on one battery. You can get the Riva for a great priced though, so its kind of a toss up.
I just like the E-Power bc it gave me what I was looking for and if you get it from CCV you get about $25 in free stuff(free Ressurector cartos, free 30ml juice of your choice, and free shipping) so its a great deal.
Either way I think you would be very happy with any of them.
Goodluck with it and I hope your enjoying your new eGo!!