I was in the same boat as you 3 months ago. I ended up getting myself an Acer Predator 15 gtx 1060. It's almost identical to what is reviewed in this video:
https://www.youtube.com/watch?v=gPmzynninPg
Overall I am pleased with what I got. It runs every game I send its way, it comes equipped with the latest version of Microsoft office and its more than enough to run league of legends. I bought this particular one because it was way cheaper than what it was competing against (it cost me $1240 and was competing with laptops in the $2100 price range) and because the thermal cooling was one of the best on the market. Your investment would be wasted if the insides melted from extreme heat so I liked not having the worry about that happening so much.
If you do want the same laptop as me you will have to shell out more cash than I did. I bought my laptop in a buyer's market 3 months ago. Now with the back to school shopping sprees starting up they jacked up the prices on laptops. $1400 is what you will pay if you buy it from Newegg tonight. But since this is a seller's market they generally plan their new releases right now. You may be able to snag one of the top-of-the-line laptops that just got released if you don't mind paying a little bit extra. Here's a fairly recent list of the top 10 gaming laptops on the market right now:
http://www.techradar.com/news/mobile-computing/laptops/best-gaming-laptops-top-5-gaming-notebooks-reviewed-1258471
That list only includes gaming laptops so don't base your decision solely on what info I provided. Do some of your own research into it. And you mention you want good performance and good battery life. Gaming laptops have very good performance but very bad battery life. Out of the box my laptop gave me about 4 hours of use before needing a charge. But if I was gaming the battery life got cut that time in half. The non-gaming laptops will still be able to play the current generation games but will tend to run hot and running hot could spell problems for the internal hardware. If you don't plan on playing games like DOOM, Fallout 4 or Farcry a gaming laptop may not be necessary if League of Legends is the most intensive game you plan to play.
I don't know the current market real well but I can point you in the direction of some youtube channels who may be able to give you some insightful reviews on the current market:
Dave Lee
Matthew Moniz
MobileTech Review
Linus Tech Tips
DailyTekk
And this is the latest video I found for the best gaming laptop in today's market:
https://www.youtube.com/watch?v=r6CHUjjkcP0