The bolt-from-the-back method usually relies on some other sliding or locking attachment hidden in the joint. The bolt serves to keep the neck in place rather than do the actual strong work. The bolt-down-into-the-block the top method relies on the bolt securing everything - usually holding the back of the heel in place.
But there are so many variations on even those two methods it's hard to say which is better. Some of the sliding track ones are adjustable if that is important to you. Personally I like the simplicity of the single bolt system, and a minimum of visible metalwork.
Jean Auray's system has a discrete bolt into the block from the front under the fingerboard securing the neck, and a sliding track system. It's very neat.
Ultimately it's a matter of how well the system is thought-out and built, and how it looks to you. And usually, the more complicated, the more costly.