Xiaomi for me.
For me it has the balance combination of powerful specs, brilliantly designed phone, and right on the budget pricing.
However the camera on these phones are a bit underpowered yet still usable for everyday use. I also would like to commend their own operating software programing, very user friendly, and lays out what you really need and use in life.
Oppo phones on the other hand are quite powerful and well built stuff. However, the only thing that ticks me off about Oppo is their pricing, I think it's waaay to expensive for a phone price. But of course not that unbelievably expensive as an iPhone! *Ahem..
Anyway, one clear strength of Oppo phones are their camera, I must say, one of the top picks in the camera cellphone perspective.