If you are interested in covers with minimum bulk and beautiful simple colors,  TPU ESR Yippee Ultra Thin Case is a right options. here are some more PLUS:

The surface feels very smooth while usage, but still providing proper grip to prevent sliding.

The color is brisk and attractive.

TPU RED iPhone 6 Case, ESR Yippee Color Series Protective Case Bumper [Updated Version [No Headphone Port Issue [Shock Absorbent [Ultra Thin [Light Weight [Scratch-Resistant [Perfect Fit Soft TPU Back Cover for 4.7 in

iPhone 6 Case, iPhone 6s Case, Clear Rose Gold SaharaCase® Bonus Tempered Glass Screen Protector Slim Rugged Apple Shock-Absorption Bumper Anti-Scratch Hard Back for Apple 6 6s - Clear Rose Gold

iPhone 6 Case, iPhone 6s Case, Clear Rose Gold SaharaCase® Bonus Tempered Glass Screen Protector Slim Rugged Apple Shock-Absorption Bumper Anti-Scratch Hard Back for Apple 6 6s – Clear Rose Gold>more info…

iPhone 6 Case,CAPY 360 All Round Protective Case for iPhone 6 4.7 Inch iPhone 6 Case(Rose Gold)

iPhone 6 Case,CAPY 360 All Round Protective Case for iPhone 6 4.7 Inch iPhone 6 Case(Rose Gold)>more info…

iPhone 6 Case, iPhone 6s Case, Samcore® 2 in 1 Shield Hybrid Case for iPhone 6 6s 4.7 inch Hybrid Dual Layer Hard Case TPU + PC Soft Hard Cover (Rose Gold Gold)

iPhone 6 Case, iPhone 6s Case, Samcore® 2 in 1 Shield Hybrid Case for iPhone 6 6s 4.7 inch Hybrid Dual Layer Hard Case TPU + PC Soft Hard Cover (Rose Gold Gold)> more info…