So, here's my final take on these two cases. Both are great. Both are very well made and should provide plenty of protection for the phone, especially if you spring for the Spigen (or similar) glass screen protector. The fit of these two are perfect for each other (of course). Note that if you buy from Spigen direct, they have 'deals' where you can order a case and a glass screen protector for a reduced cost. I wish I had known about this when I ordered mine!
The Slim Armor will provide more protection. It is also a little larger and heavier. The Neo Hybrid will also provide nearly as good protection and also adds to the size and weight. Both are attractive and you can swap out the hard plastic parts (ordered separately) with different colors if you are the type that needs to change their phone's look from time to time. Note that the Slim Armor goes on and comes off harder than the Neo Hybrid.
Of the two, I prefer that Neo Hybrid. I prefer the look and feel and slightly less size and weight. Truth be told, I prefer the phone naked, but after carrying it around a couple days naked again, I went back to the Neo Hybrid because I was paranoid.
I don't think you can go wrong with either one of these cases. But for me the NH wins out over the SA.
YMMV.