I've owned 2 magnetic trainers. Both of them were given away after a few weeks. I'm lazy to mount/dismount my bike from the Trainers and I didn't find they were very robust. I also didn't like the idea of the roller wearing out my rear tire.
I ended up buying a dedicated stationary bike with a heavy magnetic wheel. It cost about the same as a quality Trainer. Had it for almost two yrs now. Perfect for when I can't get outside to ride.....ymmv