So, as I detailed in other thread I bought a house. A house which is really freakin’ empty.
I have no actual guest bed, and will not for a while. It seems to me having one is kind of those type of things adults have. I also have a serious lack of furniture. Are futons these days better than the ones in crappy college a million years ago? Do they work as a couch and an emergency bed, or are they still just shitty at both?
if you have a futon store go there.
they would have some nice wood couch frame convertibles, heavy and sturdy with big arm rests. i’ve got one that glides in (up) and out (down).
you can also get the futon custom stuffed for thickness, hardness.
if not then go to a furniture store. they are popular enough to have quality ones there.
You get what you pay for.
That is all.
O.K. let me be more specific. As you might guess, there are various price-points. Big Lots sells them for $150 and you can spend upwards of a grand at some high-end stores. Are going to use it primarily as a couch or will it be called into duty as a bed on a regular basis? Better brands will offer a lifetime warranty on the mechanism, they will also offer a variety of mattress options. In some cases the most comfortable one to sit on isn’t good for sleeping on.
Consider a memory foam topper if it will be used as a bed for more than a night here and there.
Be certain it is a “regulation” queen size, some are narrower or shorter.
It needs to be heavy enough (sturdy) to withstand 3 people sitting on it but light enough to move away from the wall to open into a bed.
Maybe it’s just me, but the solid hardwood models look much nicer than the metal ones, which remind me of the ones found in the apartments of poor struggling artists. 
I dissent on the memory foam topper, as I personally found those to be loathsome (they tended to encourage my body into one position, which is kind of not good). What you should get is a feather-pad, which would be like having an inch of feather bed on top of the futon. Slips right on like a mattress pad.