There are many qualities you might look for in examiners – their expertise, their reputation, their experience – but simply knowing that they are a real person (not just a name on a journal article) can be comforting when it comes to your viva.
If you can, try to make sure that your examiners are familiar to you. Aim for your internal to be someone you know from your department. Suggest that your external be someone you know from conferences.
The absence of strangers could help your viva feel less strange.