We just bought DeLonghis from Fortress. One of the models had sold out, so don't wait too long to purchase because you might end up with whatever they have in stock.
Bought the DeLonghi because they had a 5 year warranty on the compressor, the sales literature had a reasonable cubic metre guide and they look nice.
I also looked on the internet and didn't find any great information. The fact that a Mitsubishi can handle a 5 room or was that "bedroom") British house really doesn't help.
And you need a cubic measurement, since air is a volume and not an area. So a square measurement only works if everyone is talking about the same size ceilings (and we have at least 2 different ceiling heights in our apartment, plus a staircase). And the last complication is that walls/doors/staircases all serve to reduce the amount the mmachine can handle; a 100 cubic meter machine could do 100 cubic metres if it had that much unobstructed space.