[LightDestory]

5 years ago I would totally agree with you. That's why I went for an older flagship Samsung phone for the price of a brand new Huawei phone. But since then I have seen things changing a lot. That those times only good Huawei phones were those their top tire models. I wouldn't even consider Xiaomi. But then I get to find out a lot about these since some of my friends bought phones from both these brands. They have been quite happy with their performance. Also, I have been using Xiaomi Remid 9 since last August and I'm seriously impressed with it. I would say these phones are better than the Samsung budget models you get for the same price.

I don't know about other brands but I think Huawei and Xiaomi are moving toward the quality phone brands, that's if they are already not there. They have already done very well at budget and medium level phone markets. I don't think they are at the same level as Apple and Samsung when it comes to flagship-level phones since these later brands have many new technologies they prefer not to share or sell. Ofc there are plenty of cheap and terrible not so well known Chinese phone brands. But I'm just talking about these 2 brands plus Oppo.

You are right saying that nowadays mid-range devices from China have the same quality of known brands... But the things that scaries me is the "post-market" experience. We all know Huawei, Samsung, Sony, Google, Asus, One Plus rollout updates very often for their devices (well lately OnePlus is lacking a bit). 

Does Xiaomi and Oppo releases update on fixed cycle? Does the phone comes in a international version (using a CN firmware is a huge risk for what I can say...)

Moreover what you pays on major brands is the software. Everyone can build a phone with good hardware, I mean Xiaomi can out-source the display from Samsung Display Inc. and the top performance CPU/GPU from Qualcomm, but what can't be out-sourced is software. You can use a AOSP device but it lacks of a lot of features!

For example:

• Google phones comes with an amazing camera apps... but the hardware is nothing special, all the good stuff comes from post-processing via software.
  
• Samsung phones comes with a lot of features that are not available on Android at all, often anticipating new Android releases. For example the restyling with a moder design, the Android-to-Desktop capability, single-audio-source controls!
  
• Asus phones, most likely the ROG phones, comes with feature-specific to gaming such as bypass battery on charge while gaming or variable refresh rate of the display
  

So does the chinese phones offer such features?

Another aspect regarding updates is: how much time does the OEM take to fix a critical bug. Most of major brand are very fast on patching daily-experiece break bugs... 
OnePlus (Oppo under the mask) are still affected by the low voice volume on What's App and it is a very old bug!

Speaking of Huawei, we must wait and see how USA will change the restrictions. Huawei is actually leaving Android in favor of HarmonyOS, a huge ? right now.