Sofa bed pull out

I have to replace the queen size matress in my sofa bed pull out. Can anyone recomend something more comfy than the standard matress. I think it can only be 4 or 5 inches thick. Thankyou...
Sofa bed pull out

I have a very uncomfortable "J" couch in my Southwind. The only way it can be slept on is by putting an air bed on it. I bought one of the beds with the air pump attached. It inflates fast and deflates really fast. Very comfortable and I know they make a queen size too. So I would suggest an airbed.