I use a BKool Pro smart trainer, and started using it when I was 396 pounds (now down to 360). I have been using it since October 2014 and not broken it yet.
This will offer up to 1200 watts of resistance.
The advantage of a trainer is its smaller size over a "spin bike", and the fact you can throw your bike into the trainer to become more efficient with your bike.
I bought and extra rear wheel to run a trainer tire as I run tubeless tires on the road; so I just swap out the rear wheel when I ride the trainer in the house (both wheels have the same ratio on the cassettes).