I have both the Mugen and the ZeroLemon and they are both fine batteries that in my experience live up to their claims.
With the Mugen(6400mAh) I get double the stock battery(3100mAh) life and with the ZL(9100mAh) I get triple the stock battery life.
One is not better than or worse than the other. The ZeroLemon simply has more juice, that is the difference. Oh and the price. Mugen being too high probably.
Just my opinion after owning and using both.
ZL is clearly better in every persepctive except for ths case..
I personally cannot justify Mugen's pricing, they are aiming higher profit margin than apple
Oh well, some people like to spend money for nothing, so be it
---------- Post added at 07:22 PM ---------- Previous post was at 07:12 PM ----------
I had few cycles so far from my ZL battery, and i could not be happier with battery life
Note: Phone is no stock/not rooted. Power saving on ocassionally
Typical battery life from my stock battery was 1~2 days with 6~8 hours of screen time
Zero Lemon
First charge: screen brightness auto / power saving / mostly wifi
over 2 days and half use with 24+ screen on time 8% battery left
Second charge: brightness auto / wifi and lte
over 3 days use with 20+ screen on time with some juice left
Since then i am using full screen brightness with lte because i cannot drain this thing
with 100% brightness with everything on i get over 16 hours of screen time, which is amazing
This is the first time that i do not worry about battery for my "smart" phone absolutely