I bought both of these cases and figured I'd give my thoughts on them. I prefer slim cases because I'm obviously into a minimalistic phone and these cases are very minimalistic. I'm very careful with my phones and just need something to protect against a drop from waist height, or maybe a door handle hitting the back of my phone while it's in my pocket. The thickest case I'd consider would be maybe the diztronic TPU case.
There are some differences in shape. The spigen case has an angled "spartan" shaped back that corners around to the sides of the phone. The Ringke case is round and curves from the back to the sides of the phone, staying truer to the actual shape of the phone.
Both phones have a "lip" around the screen so that if you lay the phone screen side down, the screen won't actually touch the table. The lip is a little more deep on the Spigen case. The Ringke case has this lip, but it's smaller so you don't notice it as much and it doesn't interfere as much when you are dragging you finger along the edge of the screen.
Lastly, if you look in the pics below, the Spigen case goes around the corners of the phone a bit more, arguably giving more protection, whereas the empty space on the Ringke case is a bit wider.
Spigen Advantages:
-Slightly more true white color
-A little more protection around the camera flash and the rest of the phone (see above)
Ringke Advantages
-Lighter in weight (14g vs 17g)
-Feels better in your hands because of rounded back, the cutouts aren't as sharp, and the lip around the screen isn't as huge
Overall I prefer the Ringke case. It's lighter and more minimalistic down to the way they implemented their logo onto the case.
There are some differences in shape. The spigen case has an angled "spartan" shaped back that corners around to the sides of the phone. The Ringke case is round and curves from the back to the sides of the phone, staying truer to the actual shape of the phone.
Both phones have a "lip" around the screen so that if you lay the phone screen side down, the screen won't actually touch the table. The lip is a little more deep on the Spigen case. The Ringke case has this lip, but it's smaller so you don't notice it as much and it doesn't interfere as much when you are dragging you finger along the edge of the screen.
Lastly, if you look in the pics below, the Spigen case goes around the corners of the phone a bit more, arguably giving more protection, whereas the empty space on the Ringke case is a bit wider.
Spigen Advantages:
-Slightly more true white color
-A little more protection around the camera flash and the rest of the phone (see above)
Ringke Advantages
-Lighter in weight (14g vs 17g)
-Feels better in your hands because of rounded back, the cutouts aren't as sharp, and the lip around the screen isn't as huge
Overall I prefer the Ringke case. It's lighter and more minimalistic down to the way they implemented their logo onto the case.
Looking forward to getting it as this phone is so light I am scared about dropping it every time I take it out of my pocket 
