@larand English, though I am able to process thought in French and Cantonese. I actually grew up bilingual (Cantonese and English), but English took over, and Cantonese got put aside because its sounds and my opinion of it weren't as appealing as English (mainly due to where I heard it — in the markets, etc., whereas I heard English spoken very elegantly in school).
I don't have a favourite language for all occasions. Italian for opera but German for Lieder/non-operatic pieces (very hard to explain why, save for my preference for bel canto opera); English for lexical creativity but Danish because of its relative lack of consonants; Latin for declension fetish and complex sentence structures (arguably, German comes close); Cantonese for very casual speech that often involves ranting and profanity.
tldr: I don't have a favourite language, just a preferred language for a given context.
// @matigo @c