Depends on location. My ex used to work for Boeing in 'customer services', which is the team who knew about all the maintenance standards and repairs. After hearing many tales I won't fly any African, Russian or budget Chinese airline for starters. Regarding Terrorism Middle Eastern Airlines such as Ethiad, Emirates, Oman Air (take a look at their options, great airline) are safer than most. Stopping over/visiting countries such as UAE and Oman are very very safe. I think I would avoid Turkish for the forseeable future though. I doubt there is any difference with Cathay, Singapore Airlines etc.

I see you live in Birmingham. I use BHX all the time and hate LHR, the journey is so much more pleasant. you can use Qatar and Emirates with IMHO no worries.