Our preference would be for a predominately white background colour for the text to sit on for good readability.
Flexible in the rest of the design as long as it includes the logo and complements our colour scheme.
Prefer simple, elegant, geometric designs rather than anything over the top and distracting.
I have attached a template that comes as standard with powerpoint that is an example of a simple geometric design and probably our favourite of the standard powerpoint templates. But it doesn't have to be too similar to this if you have a good idea for how to use our logo and colours.