A few things, which I'm not sure you're aware of. If you are interested in the top 50 programs, you are primarily going for the PhD to do research, not to teach. Either position should be fine. If you're looking into a top 20 PhD, they are going to heavily discount your work experience either way. Work experience is not a requirement for obtaining admissions into PhD programs, and no matter what kind of work experience you have, it is really only going to be of marginal benefit in admissions.. Therefore, go for the job that you think you'd enjoy the most and weigh the pros and cons of each job without consideration on how it will impact your admission into a PhD program (because it probably won't). Also, since you mentioned pay up to year 7, know that once you hit a certain age, probably about 30, it will become more difficult for you to gain admission. Therefore if you really have your heart set on academia, it is better to work for 3 years or so and then make the move. Any additional years of work experience are not going to add much additional value unless your job responsibilities change dramatically in additional years, and even then it may be questionable the value added to the PhD. Use your best judgment.
For admission into the top 20 programs, the most important criteria are likely to be a GMAT score in at least the 95th percentile, a very good academic record (probably at least an A- average for undergrad, and close to 4.0 for your masters), a reputable undergraduate and masters institution (state flagship universities or strong private universities), and strong letters of recommendation. If you have any research work experience that will benefit you a lot more than any industry work experience will.
If all you really do want to do is teach, then I would not recommend going back for a PhD, and you definitely won't make it into a top 20 if that is your goal. If you want to mainly teach you can do so with your masters, and if you must get your PhD, you will probably be a better candidate for schools outside of the top 50.