I like the kind that are:
happy to be at the hospital,
don't whine about the food or how they don't get everything their way every second,
are polite and sincere,
aren't in your face constantly expecting attention,
are med- and ward routine-compliant,
don't give you a hassle and pressure you because they think they deserve everything,
don't pick fights,
are enthusiastic about getting treatment,
don't sit around like lumps all day long,
don't talk at the tops of their voices all the time,
don't ask inappropriate questions or act inappropriately,
understand when you're busy,
don't try to tell you how to do your job,
clean up after themselves,
have good hygiene,
are supportive of other patients, ...
I probably missed something.
I work in a psych hospital, by the way.
I might be a little redundant, but you get the idea.
don't have a history of hurting innocent people,
I could go on forever.