I consider Shiites more hostile, although they are only 10% of all Muslims.
Shiites are not more hostile - at least than Sunnis. They just aren't hypocritical.
This means they do the very same as Sunnis but admit to do it.
Radical Islamists are a threat everywhere, and it doesn't matter whether they are Sunni or Shia. On the other hand, the moderates can be both Sunni and Shiite. For example, secular leaders such as Bashar al Assad are Shiite. Abdel Fattah el-Sisi, who restored the secular rule in Egypt is a Sunni, and so was Saddam Hussein of Iraq.