kunena forum to phpbb3 or smf

I have a kunena forum that somehow will get a little problem with the government so i want to protect my members. Many are suggesting us to change the forum platform to a much better. Do you think my forum can get hacked easily by the government somewhere in a 3rd world country that will trace my members or anything. Ist really kunena not that secured? If ill change my forum to another flatform then what would you suggest? I tried phpbb3 but i didnt like it but i can use it if its the best platform. While smf for me looks like a little bit like kunena. Can you also guide me a link how to convert it. Maybe phpbb3 is the best choice for me so it will be easier for me to learn as i used it before. i really need your help. thank you