LLC for each Rental or Series LLC

Forget the fact that some of you dont feel that using seperate LLC to hold each rental property is needed, consider the following:

Concerning Liability, which offer more protection?

1. A series llc

2. a standard seperate LLC for each property

Does anyone know if there is much caselaw to support liability seperation within a series LLC?

It seems as though the extra fees to have multiple LLCs is worth the added benifit as a more "tried and true" system.