Same here, I have the Anker 6400 and it's great. I use it as my daily driver, it still fits in my clutch and I know it will go all day without worry. I had great battery life on the stock battery for about a day but once I added apps, it went downhill hill quickly. I usually buy extended batteries as soon as I order my new phones. I've tried all the generic and found that Anker was the most consistent. I also have the Zerolemon 10,000, but i use that for power outages. It's a damn brick! But it does last for 12+ hours on onscreen time!
With the Anker I easily get 8 hours SoT and 20-24 hours of battery time.