I'm deciding on a guest bed arrangement for a small room. Should I get a futon, sofa bed or pop-up trundle?

Posted under sofa futon

We recently got a beautiful dark wood futon from freecycle but the mattress had to be thrown away because of pet smells. We have it in home office but needed extra sleep space for occasional visits from grown children. We went to a local furniture store and found out that they have new futon mattresses with springs built in. It is really thick and nice. It cost $200.00 . We have already had guests sleep on it and they said that it was extremely comfortable.