I'm going to chime in and agree that mags are definitely not the "silent choice" but they are pretty quite when submerged and secured so they arent vibrating all over the place.
I think the mag pump is a great beginner or budget minded return pump. Enough experience is out there to help people line the proper model up with their setups, they seem to be the only tried and true reliable submerged pump (although there have been bad apples), you dont need bulkheads to run it and there isnt much sticker shock associated with the purchase.
The larger mag pumps I believe get the worst reps too, because they stay relatively compact but the output keeps going up and I think the trade off is noise etc vs a large external pump. But as far as the smaller ones, I've had a mag 9.5, 7, 5 AND 3 in my past, and they all did the job to satisfaction at the time. I use all external pumps now, but thats preference, not neccessity.