Japanese (漢字) Japanese (かな) Remarks Meaning
面倒くさい めんどうくさい $$$ general word for annoying.
煩わしい わずらわしい an annoying process (paperwork, say) which isn't hard but is really petty and time-consuming and full of trivial rules.
ややこしい annoying because it is a difficult and confusing process, which never seems to end. 
厄介(な) やっかい(な) bothersome. A little more formal and less mutliusage than the daily used (or heard) 面倒くさい