Go Glaurung go!
Glaurung is the more mythical and awesome as a mere sentiment or feeling the reader has. The name of Glaurung * rings deep into the layers of the unconscious parts of many languages inciting something like a premordial fear and awe; it calls forwards an
ur-creature you will tremble in front of, whereas Smaug sounds more like a cheap rendering of some slimy or just bare un-nice syllables in English.
*remember to spell Glaurung correctly: like keeping the vowels separate: 'a' as wide as 'u' in "but" and 'u' as narrow as 'u' in "put".
++ Glaurung