Hey Ben. I started with a V2 kit also. A lot of folks here knock it, and their batteries are expensive, but overall I think it is a great kit. They use the 808 (KR808D1) batteries and cartomizers, so any other 808 gear will be compatible. A lot of people like the V4L (Vapor 4 Life) cartomizers, which are also 808, but I am not personally a fan. The Bloog, Smokeless Image (Volt), and Halo gear is also 808-based, so your V2 gear is compatible with their stuff too. You can also get excellent 808 blank cartomizers by Boge (Liberty Flights is a good vendor for these) and SmokTek.
Tastes vary. One man's trash is another man's treasure. The only way to find what YOU like is going to be some experimenting. I have tried all the above, and my favorite 808 cartomizers are, in order of my preference: Boge, V2, SmokTek, Bloog/Volt, and lastly V4L. Again though, you have to experiment to see what you like best.
All of these cartomizers I ordered blank/empty and filled with good juice that I like. That is a whole other conversation to explore.

I have gone through dozens of juice samples and my personal favorites are from Copper Creek, Alien Visions, and Vermillion River. Yet again, you are going to have to sample and experiment to find your taste preferences.
As for battery life, the "standard" (78mm) V2 batteries are ~280 mah. This is about 2.5 - 3 hours of usage, depending on how heavy of a vaper you are. For higher capacity batteries there are - you guessed it - a bunch of options in the 808 family. Echo, iGo, vGO, and Elite are all 808. SmokTek sells an 808-threadded eGo. After trying all kinds of different batteries, my personal preference is the Go-Go (from Discount Vapers) with an 808 adapter. One battery charge easily lasts all day, if not two. I still sometimes use my standard (like you have) V2 and Bloog batteries, but 90% of my vaping is now on my Go-Go batteries with either the Go-Go cartomizers or 808 cartomizers. My most satisfying vape is a Go-Go battery, Boge LR 808 cartomizer, and Copper Creek's House Blend juice. As usual though, you have to experiment to see what you like best.
In short, the V2 is a good kit. I like mine very much. Yeah, their batteries are expensive, but they got me off cigarettes - and that is priceless! I will buy more V2 blank cartomizers, but I would not buy more V2 batteries.
Welcome to vaping! I am relatively new too (about three months) and experimenting is part of the experience!