Which workout is better?

When I go to the gym, I spend 21 minutes riding the recumbent bike in random mode. That means it randomly gets easier and harder to pedal. When it gets harder, I know that my pedaling slows down. Unless the room is hot, I seldom break a sweat during those 21 minutes.

When I ride my real bike (a gearless, back-pedal braking cruiser), I can only make it about ten minutes. During that ten minute ride, I am going up and down hills. Going down hills I often don't pedal but ride the brake so I don't crash at the bottom when I need to turn. Going up hills or on flat surfaces, I pedal. My ride out ends on a certain hill with a rather gentle slope. Eventually my thighs start to burn like fire so I give up, turn around, and go back. On the big slopes (which is most of them), I get off my bike and walk it up the hills. I know; it's very pathetic but I wouldn't ride at all if I didn't do this, and surely this is better than nothing. I know it's time to walk the bike when it starts to teeter because I am going so slowly.

Anyway, by the time I get home, I am sweating, my throat hurts, I am gasping for air, and I pretty much feel like I have the flu. If it is at all cold, my ears ache. The thing is, I am gone and back in literally 10 minutes. I spend 21 minutes at the gym riding the bike without breaking a sweat. Which is better?

(Also at the gym I use the machines for 15 minutes that build muscle, but I am keeping that out of this comparison.)