I can't recommend a specific unit, I have experience of using several over the years, and they appear to be 'much of a muchness' AFAIK, but I can give you some things to consider:
1) They are noisy, even those badged as being 'quiet' or even 'silent'. This is because the compressor which is usually located outside of the building is contained inside the portable units. I would not recommended them for sleeping areas. The noise will keep you awake instead of the heat.
2) They come with various cooling capacities and the price usually reflects the capacity. So make sure that the one you get is of sufficient capacity for the room.
3) They are a comparatively inefficient form of air conditioning. Air from the room that you have paid to cool is sucked into the machine to cool the condenser and is then blown outside through the hose. The quantity of cool air lost to outside is quite significant.
4) Because of the air being blown outside, air must come in to replace it. If a window is open to let the hose out, that is the easiest route for it to come from. If the outside air is hot, any opening around the hose that could let hot air in must be sealed up. Kits are available for this purpose that have a zippered opening for the hose. They are not brilliant, and a bit of a faff, but much better than nothing.
5) Consider a split air conditioner, the indoor part is so much quieter than a portable unit, and without needing the hose, windows can stay shut meaning all of the cool air it produces stays in the room. The purchase cost is similar, but because of the refrigerant gasses they do need professional installation which can usually be done in a day.
