I would get a window mounted AC. I had a portable unit, and hated it. Not only do the portable cost more, it's not very 'portable'.
What those pictures don't show you, are the HUGE GIGANTIC TUBE that comes with the portable AC. After all, the "hot exhaust air" needs to go somewhere. Namely, out the window.
So you have to hook up that big tubing to a nearby window. And that's not as easy as it sound. Some suggested using duct tape to get a proper seal.
Not only that, it's pretty loud too. Having a portable unit sitting in the room with a tube sticking out the window, not a pretty sight.
We do have a central unit and I've have been using that this past summer instead. The problem with this is that is cools the entire house, instead of a particular room.
Good luck with your decision.
Pic of what I had.