Only traditional. My knowledge of simplified, and the debate in Chinese academia about their real value, actually stems from discussion with Chinese linguistic experts, but I have no personal experience with simplified Chinese myself, except casually.
I studied three and a half years of traditional characters, switched to simplified when I went to China, and then started studying Japanese, which uses a mix. I definitely am glad I studied traditional characters, but I feel at least for me, they are much much harder to learn, but that could be different for different people.
Out of curiosity, have you tried learning both simplified and traditional?