Above ₹5,000, a Father's Day gift for a father-in-law gets judged on whether it works, not on whether it was thoughtful. That is actually the easier brief. You are no longer guessing at his taste in shirts; you are buying a machine with a spec sheet, and the spec sheet either matches his flat or it does not.
So start with the room, not the brand. Six of the seven picks here are air purifiers and they are not interchangeable: the Levoit covers 183 sq ft and is really a desk unit, the Honeywell 235 sq ft, the Qubo 400 sq ft, the Eureka Forbes 480 sq ft, and the Jafanda claims 1,190 ft² at one air change per hour. Measure the room he actually sits in on winter evenings and buy the number above it. Buying under it is the single most common way this gift disappoints.
The second question is whether he wants a phone involved. The Philips deliberately has none — the listing says no app is required, controls sit on the device and the air quality reading is on its own display. The Qubo and the Jafanda are the opposite: the Qubo is app-controlled with live PM2.5 and scheduling, and the Jafanda adds Alexa and Google Assistant on top of its own app. Either is the pick for a father-in-law who enjoys that sort of thing. There is no right answer here, but there is a wrong one for a specific person.
Watch the warranty lines, because they are wildly inconsistent across this set. The Levoit states two years and the Safari set three years international; the Philips, Honeywell, Qubo and Eureka Forbes listings state no warranty period at all; and the Jafanda advertises five years in its title while its own description describes one year plus a free extended year on registration. Confirm before you buy, and keep the invoice.
The Safari trolley set is the outlier and it is here on purpose. If your in-laws travel at all, three matched hard cases with a 3-year international warranty is a better ₹5,349 than any purifier — a gift that goes somewhere beats a gift that sits in a corner.