TOEIC is mainly aimed at intermediate students, which may be enough for your purposes. Personally, I much prefer IELTS and TOEFL for assessing advanced English learners. TOEFL is American English, and useful for study in the USA. IELTS is mainly UK English, useful for study and immigration in British Commonwealth countries. From what you've said, you should simply find out what employers in your area are looking for. One more thing -- government bureaucrats may be impressed by exam results, but in private industry, the employers will judge for themselves whether or not you can handle the job. If your skills aren't up to snuff, a certificate isn't worth the paper it's printed on.