I have a gym quality recumbent bike - LifeFitness R7i (it's about five years old so the model # is probably out of date). I've owned 'home' exercise bikes before and found them to be poor quality and uncomfortable so was willing to spend the money for the quality and durability. I haven't been disappointed.

It's as smooth as silk, built like a rock, and hasn't needed any repairs or maintenance.
The resistance goes to 20, though I've never gone above 6 for long, so there's resistance to spare! It doesn't need to be plugged in.
I saved several hundred dollars by buying the model without the built-in heart rate monitor. It came with a Polar HR strap that reads out on the display, so it's no big deal that there aren't built-in monitors in the handles.
Highly recommended!
This is the 9i, identical to mine but with the built-in HR monitors in the handles.