II currently have 3 air purifiers installed at home in the last 1 year - The Coway AP-1009 (this model), Phillips 1000 series, and Mi 2s. All 3 are in the 8000 - 15000 INR price bracket.
This is my take on Coway vs. the other 2:
- Customer support is by far the best in Coway. They are proactive, friendly, and transparent - just how customer service is supposed to be. Phillips customer service is the worst (in Chennai at least), while Mi is in the middle.
- Customer service: Coway hasn't had any problems yet so I haven't had a chance to test out service levels. Due to frequent power fluctuations in my area, both the Phillips and Mi 2S suffered a short circuit and stopped working. Upon returning the units to their respective service centers, Phillips service center in Chennai has no infrastructure at all, and they took more than 2 months (!!!) to repair, plus I paid extra for the circuit board (Rs. 1500) which was apparently not under warranty. Mi 2S didn't have any service at all - they simply replaced the unit with a brand new one once they found what the problem was (took about a week). This could be due to them not really having a service/spare parts license in India due to it being a Chinese company, but I am just speculating here. As for Coway, the service apparently has at-home repair service included in case something goes wrong, which is a big big plus in my book.
- Features: In terms of actual cleaning ability of PM2.5 pollutants, the Coway seems to work the best, since it has a 3 stage filtration. Philips has this too, but I am not sure it cleans as good (it's about 20% smaller), while Mi 2S just has a circular HEPA filter and no pre-filters as far as I know. So for purifying ability I'd trust the Coway the most - technically speaking.
If you read online blogs and journals, you'll quickly realize the 'auto' mode in most commercial air purifier doesn't really work to clear the room of pollutants. What I usually do is leave all the purifier in their highest fan settings for 3 hours before bedtime, and put on the auto mode during sleep so it's not too loud. This is the only solution for Phillips and Coway. For Mi 2S, it can connect to your phone with its own Mi home app so that you can remotely control the settings and set timings on the purifier. The app has a quirky UI and layout though, so consult online blogs on how to use it. Mi 2S also has air quality indicator readings that the other 2 lacks. While this is really great in theory, again if you read online reviews you'll see that these numbers are inaccurate and really not representative of actual air quality as measured by a proper instrument. Having said that, I wish the Coway had some sort of air quality meter reading.
Coway is the best designed, it is beautiful and the lights are very pretty. You can turn them off if you prefer pitch dark like me (however the tiny but bright LED light that signal on/off cannot be turned off). The Mi 2S is a large cube block, which is a simple but pleasing design. The Phillips I would say is the least pretty.
Coway has all buttons on top, they work great and have good tactile response. Phillips is the worst - the buttons are vague and lack any feel. Mi 2S has just one button at the top which works great.
In summary, I am happiest with my Coway purchase compared to the other 2 because of it superior performance and excellent customer service and support. Some features are missing and if those are added it would be the best in this price range. I will definitely not buy Philips again and Mi 2S is a question mark in terms of performance.