How to choose between upright and rebent exercise bike?

I have a sit-down job at home and have heel spurs on both feet, which doesn't help my morbid obesity. I want to get an exercise bike for when my feet really hurt, but would like to know opinions on upright versus rebent exercise bikes. Rebent might be easier on the tushie and I could use hand weights more readily, but an upright is a little smaller. Help!