The Redmi 1s has a pretty decent camera, tbh. So I'm not too sure you are going to get a noticeably better one within 10k.
I'm not too sure the cam specs are going to be too different on any of the sub-10k phones. The most recommended phone for photography was some Lumia model which had a larger sensor ..... & that was/is 20k/40k-ish iinm.
The reason you see varying reviews for the same camera is - a. different lighting conditions & b. different expectations.
So, for eg, nowadays any cam is great in broad daylight - be it a phone or a p&s. The difference lies in low light shooting. When it comes to low light photography with a phone, it primarily depends on how the software handles things rather than any actual hardware differences. Thus one phone may pump up the iso to make the photo brighter at the cost of noise while another may not. Expectations vary in that some people prefer the brighter picture while others may prefer the relatively noise-free one. Some people like a more saturated image while others prefer greater accuracy.
On
this thread where I compared the 1s with the OPO, you can see that the reactions vary. You can also see that the OPO gets brighter images in low light mainly on account of the pumped up iso. In that sense it was actually a bit unrealistic because the 1s images' exposures were closer to what I perceived in reality. Now who's to say that one is preferable to the other? Different strokes for different folks, if you ask me.
So I'd say rather than looking at the h/w specs, you should probably stress on s/w features that might be beneficial to you. (For instance, my wife's Mi4 has a very accessible exposure compensation dial which helps tremendously.) Look into how aggressive a s/w is when it comes to things such as noise, saturation, temperature. Also ask yourself if you are a pixel peeper, at what resolutions you will be looking at the photos, at what screen size, what will be the size of the prints if you're into printing photos, whether you are okay with post processing images or not, whether you will prefer greater manual controls vis-a-vis iso, aperture etc. ...... & the like.
Of course, what I've said is very debatable but it's how I'd approach a similar purchase. You should also look for sites that compare phone camera samples such as
this one for a more objective view. HTH.
