Skype or tango?
I use Skype, but that's mainly because a lot of the people I talk to already have a Skype account, and they use it on their phone and/or computer. Next to none of them use Tango, so it's one less app/account to worry with.
Current lineup: Galaxy Note 2, MotoActv
Previous smartphones: Galaxy S3, One X, Droid RAZR MAXX, Galaxy Nexus, Rezound, Galaxy Note, iPhone 4S, Droid Bionic, Stratosphere, Droid Charge, Vitality, Droid Incredible 2, Thunderbolt, Palm Pixi Plus, Droid 3, Fascinate, Droid Incredible, Droid Pro, Droid 2 Global, Droid X, Droid, Treo Pro, Touch Pro 2, Touch Pro, Q9m, XV6800, XV6900
Previous tablets: Transformer Pad TF300, Evo View 4G, Transformer Prime, Transformer TF101, Thrive, gTablet