While the dual hose ones are better, I agree that these all kind of suck because you have the compressor inside and it's always the loudest part of an AC.

If you get an expensive one with both in and out ventilation through the window it can be good. But you’re spending a lot more than just a window AC at that point. The cheap ones actually vent your cold air outside.

I got a couple of $150 cheapo units at the big box stores to supplement our central air during heat waves, have been just fine. 5k or 6k BYUs at least.

Just don’t get a portable unit. They suck and are just a waste of money most of the times.

Get a dual-hose unit if you get one. There are a lot of companies selling single-hose units. Those are a lot less efficient and aren't much cheaper. I would guess that in a situation where they get any kind of meaningful use, a dual-hose unit pays for itself quickly.

I don't think I'd agree that they suck, but if you can use a window unit

not all rooms and windows are amenable to this

you normally want a window unit instead of a portable unit, unless you must take down the AC unit on a regular basis. Less noise inside, more energy efficiency.