Utility : static class with static methods OR non-static class with static methods

Best design solution amongst the below for a Utility Class (say logger class):

1. static class with static methods.
2. non-static class with static methods with a private constructor (throwing method not implemented)
3. non-static class with static methods having a singleton

I saw this answer but found it oversimplified & superficial.

Please elaborate. Language used :- C# (just for reference)