You have to expect your examiners might have criticisms. You can also expect they will be fair in the way they communicate them to you.
You don’t need to be particularly thick-skinned to take any critical comments – but you need to expect your examiners might have comments and corrections for you.
Perfection isn’t realistic, but neither is a totally critical appraisal of your research.
There are plenty of interesting reasons why Dr X or Professor Y might be good examiners:
You don’t get to choose directly. Most candidates can at least have a conversation with their supervisors about who they think would be a good choice. Think through what you might look for, and see how that conversation goes.
There are also interesting reasons why Dr X or Professor Y might not be acceptable as examiners:
Depending on the rules of your institution, these possible conflicts of interest might disqualify them from even being considered. If you’re concerned at all then it is worth checking.
The first list comes down to preference: the kind of examiners you want depends greatly on what qualities you see as being valuable.
The second list comes down to policy: some people won’t be acceptable because of how you’re connected to them.
You should definitely think about the first list in advance of your viva; in some cases the second list will be just as valuable to narrow down options.
There’s a common worry among PhD candidates that examiners see all and know all. They have understood your thesis perfectly even before they’ve finished reading it. They can find the problems that you didn’t even notice. Their opinion is what counts.
A favourite analogy that helps me tell others about viva prep is to think of their thesis as a star, and think of their examiners’ work like constellations. Your examiners know more not because they are innately better than you, but only because they have had longer to do their work than you.
Keep things in perspective. They have experience; you have expertise.
Like the perfect thesis and the perfect viva, perfect examiners don’t exist.
You can make a list of things that might be ideal (an expert, an experienced academic) or preferable (someone who is nice, someone who could be a good reference), but they’ll never be perfect.
Steer their selection in conversation with your supervisor. Find out what you need to know about their work. Get ready to talk with some experienced academics about your PhD work.
They’ll be good, maybe great, but don’t put them on too high a pedestal.
They’re not out to get you, with malicious ideas and opinions. You’re not locked in their sights, and they’re not on a mission to make the viva uncomfortable, unenjoyable and un-passable.
They have to do their job. They have to examine your thesis and you. They have to be experienced and knowledgeable, they have to be prepared for the viva. That can sound intimidating, but all of these are good things.
Remember that you’re the expert in your thesis. Your examiners might have more general experience than you, but no-one else in the world has as much experience with your work as you do.
Your examiners are not faceless and unknown. See what you can learn about them and their work. Explore what you can find that will help you feel confident meeting them to discuss your research.