I have both. Both have their merits, but I'd go with rollers.
A. If you can ride a bicycle on a road, do it. Nothing beats miles on the road.
B. A Turbo trainer lets you ride to destruction... but that's about the main and only advantage over rollers. Turbos can be noisy, are extremely boring to ride... I'd almost rather be fat than train like that. To be used only if there's nothing else and you really do take it all more seriously than is healthy.
C. Rollers are less about riding to destruction/collapse and more about getting some work done but also keeping your mind on the job, thinking about position, steering, wobble at speed... all that jazz. It can be fun and there are comedy moments too.
So my list in order of fun and function is:
1. Riding outside on a bicycle.
2. Rollers.
3. Eating dried cat food and watching a fishing show on freeview while someone throws cold custard at me.
4. Turbo Trainer.