We are asked constantly which unit to buy, and we will tell you on the telephone at no charge, because the alternative is being asked to fix the wrong unit for six years.
Three things matter more than the brand. Capacity, which should be calculated for the room rather than rounded up. Whether it is an inverter unit, which costs more to buy and about a third less to run and is worth it for anything used more than four hours a day. And whether the brand has parts and a repairer in this country, which is the question nobody asks and the one that decides whether a five year old unit is repairable or scrap.
That last point is worth being blunt about. There are units sold here whose fan motors and boards cannot be bought at any price, and when one fails the whole unit is thrown away. We will tell you which ones we can get parts for from our own experience, not from a brochure.
We will also tell you when a unit is not worth replacing yet. A twelve year old unit that has been serviced and holds its gas is often a better proposition than a cheap new one.