Aim

Go for Coway AIM(see the comparison with Coway airmega 150) or xiaomi. Its worth it to stretch the budget as it will be work for years. I initially got Xiaomi but the reading for PM on display looked fake(it automatically decreases even if there is pollution in the room) so I got Coway but it has go

Sorry to mis-guide you bro. You must get a replacement. The panel gap must be uniform, I checked mine carefully after seeing yours. I will attach pictures of my 5 year old Coway AIM-150 with replacement filters inside it with panel closed, these filters are thicker but still no panel gap like yours.

Coway AIM is good at 12k. Whatever you buy, make sure it has 3 filters (HEPA + carbon + prefilter), the filter replacement cost is under 3k, and you can monitor PM2.5 (either on the device or via app).

That is enough, you just saved money by not buying those purifiers that has digital meters. BTW that colour indication should work in other modes as well. EDIT : if you can return it get the Cuckoo Respure, that has color indication and more value for money, Plus that has detachable pre filter which

How's your ventilation at night? CO2 is often a major problem for sleep quality. An air purifier won't help with that. Opening a window will probably improve sleep for far more people than an air purifier will. Concerning air purifiers, Levoit 100s or 200s would be good choices for the entire room.