I have been using rollers the last couple winters (remnants from my riding days in the eighties).
The rollers help me for my pedal stroke but don't have much resistance.
They do take a higher level of concentration at all times.
Heading out today to purchase a mag trainer to supplement it.
One of the reason is also that i like to cross train for general fitness during the winter and go back and fort from treadmill to bike to free weights in 15 minute segments.
Have done hour plus sessions on the roller but get really bored.
Having the spare bike setup on the trainer , i will even be able to just hop on in regular sneakers for a five minutes easy cool down.
I may also pick up a used rear wheel and use some inexpensive tires for the trainer.
In regards to type of trainer (mag , fluid). The Cycle ops mag trainer was recommended to me by a former pro. This is the model he uses for group trainer sessions at his bike shop.