I agree with Sarah. “For” is a bit old-fashioned, although still used for variety. “As” is a bit formal, so it works better in writing than in speaking. “Since” is a popular option if you get tired of “because.”
(Before a noun, we have additional options, such as "due to" (usually something bad) and "thanks to" (usually something good).
Pronunciation notes:
“Because” is often reduced to “‘cause” (or similar) in speech (not acceptable in writing).
Note that “because” does not rhyme with “cause” in standard English pronunciation. Accordingly, “‘cause” does not sound the same as “cause.”
The following is RP, but a similar distinction exists in US East Coast accents, as well as in some other American English accents:
Because /bɪˈkɒz/
Cause /kɔːz/