using a bicycle is always my last choice, and I only use it when all the other pieces of equipment are taken and I am desperate for cardio.
Since I have a very poor relationship with bicycle seats, I tend to use the recumbent (but only kicking and screaming and with an eye on the other cardio options).
It really depends on your client. People with knee problems, obese clients and seniors often prefer the recumbent. I try to avoid bikes with most of my clients as they do enough spinal flexion and sitting during the day. I only have those who are really uncomfortable with other aerobic options use a bike.