A trivial question, but something I've been curious about for a while.

I prefer to see them as upper case, purely for aesthetic reasons. Since numbers are typically of equal height, I like the letters in hex values to also be the same height.

Code:
0A B2 3C FE    // nice and uniform

0a b2 3c fe    // sloppy-looking (in my opinion)
However, I've seen many instances of lower-case, both in source code and as program output.

Which is your preference, and why?



Bonus question: What about the 'x' that denotes hexadecimal? I like that to be lower-case, as it is an indication of base and does not contribute to the value:

Code:
0xFF    // I prefer to see this...

0XFF    // ...instead of this