In case you're sick of cell phone contracts - or have kids wanting phone but you don't want a 2 year agreement - I bought a Straight Talk Sim Kit at Walmart ($60) which included:
Regular and Micro SIM for AT&T (This will get LTE)
Regular and Micro SIM for T-Mobile (This will only get 4G)
1 month unlimited talk, text, data - $45
I chose the AT&T Micro SIM and paired it with my Nexus 5.