Which type of seal on a French door refrigerator is more reliable?
I have only had experience with the rotating strip on two different brands of French-door refrigerator. On both, the flipping mechanism works well the vast majority of the time.  However, it occasionally will get bumped to the "closed" position while open, preventing the refrigerator from actually closing correctly. It simply must be flipped back to the "open" position and reclosed. The seal works well.

On the first refrigerator, we had it for several years and never had a repair issue. On the second, after about two years, one of the plastic hinges that hold the flipper to its door has cracked. Despite this the mechanism still works but is a bit more prone to the mis-flip issue. Has not been replaced yet, and the service says the whole flipper mechanism needs to be replaced. Cannot speak to whether this is a fluke or a common problem.

Overall I like this type of mechanism, despite the problem, but have nothing to compare it to.