I try to carry as little in my pocket as possible. Thick wallets in your pocket can actually cause problems with your posture and point you to a chiropractor.
I’m a big fan of the Tyvek Slim Fold Wallets that began on KickStarter. They’re paper thin but super strong and last six to eighteen months. They cost about $20 – $25 and come in a variety of colors.
They’ve also now got a stronger soft shell version which I haven’t tried: