What is a good brand of air conditioning in Thailand?

Idd, Daikin or Carrier (slightly less expensive) are the better brands
Plenty of budget air conditioners such as Beka and Central Air
And in between the other brands….
The home pros and thaiwatsadus always have offers, especially now that the cooler period is approaching
But they don't always want/can't install

What is also important is that you get the correct BTU for the room in question
Calculate it yourself and keep in mind that a long room is more difficult to cool than a square room
so measurement shows the same BTU, but for a long room that is a waste of money.
Buy that lower BTU and put a fan halfway across the room if necessary

The best and very economical air conditioner is the dual inverter from LG. This technique saves a lot of energy. Very economical and quiet. Plus perfect filter system

Mitsubishi and Daiken inverter are the top. More expensive, quieter and more economical (inverter).

The Chinese Haier is cheaper but should not be in the shadow of the first two in terms of quality.

Maintenance will be more or less the same for all brands. This depends more on the use than the brand.

Repairs will probably be needed sooner for the Chinese (if they are possible at all).

Depending on the proximity of a larger city, there are also often second-hand A/C for sale.
The supplier supplies and installs these.
For example, we bought a small set at the office for a room of 6 x 3 meters for 7600 THB.

I live in Indonesia and have been using 16 Daikin units in our diving resort since 2019. These are 14 x 2 HP and 2 x 1 HP units, HP they call it here, all inverter type. I would have to look up BTU. Inverter is best because it “switches” in terms of strength, not just on/off.

In the 4 years so far, although little use in the bungalows during Covid of course, I have had to replace a capacitor in an outdoor unit (ODU) once (easy and costs almost nothing), but also twice a whole printed circuit board, both in an ODU and in an Indoor Unit (IDU). Both times the circuit board was burned out at the location of the main chip where a blackened little gecko (tjiktjak) turned out to be stuck! So the fact that they can get in between is perhaps a weak point, apparently insufficiently shielded due to cooling (and the heat that the gecko seeks out there?) Price of new motherboards (PCBs) is approximately 1 Euro!

Apart from that, I don't think 3 problems out of 14 units in 4 years right on the beach (salty sea breeze) is bad. By the way, most here swear by Panasonic as the best brand, but it is about 20% more expensive than Daikin. Perhaps because Daikin does not yet have much of a foothold here and probably. wants to compete. What about Panasonic? I swear by that for all switch and socket fixtures. Have been using it here at the seaside for almost 20 years, never any problems.

More details about the units I use, Google my name (Ton with 'n N, and where I sit “Pulau Weh”)

Of course they don't do that for free Dennis.
The basic price includes installation because buyers simply do not have the knowledge and equipment for installation.
If you want a take-away price, you can simply make that clear and you will usually get it.
Most of the warranty will then of course be void.

I also had the burnt circuit board once, Ton, the thing had been hanging for less than six months because of the gecko.
Renewal costs three thousand baht.
Very annoying.

As far as brands are concerned, I think there are three brands that are very good, of which I have the brand mentioned by Dennis, a matter of taste in terms of appearance.