You use the tenth. This is your career we're talking about and that is signified by the tenth.
The sixth used to be associated with slaves (and still is) but few of us legally have slaves these days. Slaves are people who do the work for you to ease your life. Now such people might be servants (such as the childminder, au pair, or the woman who comes in once a week to do the cleaning). If we run our own business, we have employees and they do the work for us, so they're sixth house too. If we are employed in a managerial capacity, we might have a team of people to support us, they are sixth house too. If we call out a plumber or TV repair guy, then they too are sixth house - they do the work for us.
What the sixth house is not, is co-workers. That is a modern error. Co-workers are seventh house - they might work for the same company, but they don't work for us (unless they're reporting to us, in which case they are a 'slave' and are sixth house).
You always look further. The Moon might act for you or the significators may be linked through antiscia, or there may be collection or translation of light.
Ignore pretty patterns. They don't tell you anything.
I'm not going to tell you anything more because it will influence your performance in the interview. Either you are sure you're going to get it or sure you're not. Both are exactly the wrong attitude to take into an interview. Read the job description, have your CV committed to memory and have reasons already prepared as to why you fit the person specification perfectly and why your experience/knowledge/enthusiasm are exactly what the job description calls for and shows your competence to do the job. That's the approach whether you're going for an interview to become the next CEO of Apple, or for an interview to be a part time cleaner at Macdonalds. You have to sell yourself with reference to the job and the person they're looking for.