If each policy offers the same coverages: contents, liability, travel, and accident.. then the policy that pays the most for those losses is best. If they all pay the same, then the policy that costs you the least is best.
It sounds like the policy that is for those people over 50 would cover the same as the policies for those with bipolar or epilepsy.

I hope that helps.

As far as taking out more than one policy, it would be wise to contact the insurer and ask how that works. It could be that more than one policy is permitted.