For $100 less, I would seriously consider the ZenPad.
Walk in-store and give them a try, see if the Tab S2 feels like it is really worth $100 more than the Z580C.
As for "our thoughts", your tablet choice should be based on your own preferences, not ours. If all you want is a mainstream tablet to do mainstream stuff, the Z580C should be more than fine. If you are a heavier multi-tasker/gamer, then the S2 with 3GB RAM might be a better choice.
At $300, you may also want to consider the Z580CA which has 64GB of eMMC, 4GB RAM, a faster CPU (than the z580) and better cameras.