I searched for a long while to find a decent replacement battery for my phones: Galaxy,Droid,w850i,e71 etc.
I dont think the problem is with the battery themselves, I suspect its the cellular chips and CPU/GPU that may not be quite as power efficient as tier 1 brands. For instance, I notice a significant hit when keeping GPS on (which really shouldnt use that much power) and when gaming, my MTK6575 battery will drain ridiculously fast. Then again, even an iphone 4S will only last 3 hours of 3D gaming and most >4" smartphones will struggle to last a day under heavy use, its not like this is an issue only with chinese phones.
Also note that with most MTK657x phones, you get 2 batteries. There is no easy way to charge the second battery, so its not as useful as it might be, but at least you already have a spare. By the time both batteries have died, the phone will be outdated anyway, so I dont worry too much about it.
Last point, if battery life is a prime concern, have a look at the Oppo T29. It comes with a 3000mAH battery.
http://www.youtube.com/watch?v=gGHKVR__ii0
Unfortunately its running a customized android without play store atm, so Id wait for a modified ROM, but im keeping an eye on it.