There is pros and cons of each one you listed IMO
1 Speck candy shell. I cant speak for all styles and colors but i know basic white one i had showed scratches LIKE CRAZY !
2. UAG, all I know personally is that the UAG i had on my samsung years ago Was in hospital nurse took photos of me in traction unit ( dont ask lol ) and she dropped it on floor this was my galaxy s4, I had basic film protector on it No damage nothing. Iphone one i had the glass protector on my niece was sitting on floor in kitchen well i was baking ( like foot drop ) onto the floor my gass shattered. Cant say which caused what but i have switch to otterbox commuter.
3. Otterbox Symmetry is great just not much lip for screen protection if you dont drop your phone etc its great case personally would say that one.
4. Magpul know nothing about.
pros and cons to everything think about style you want protection you want.