Can you get a great advisor at a mid-tier place and a strong guarantee that you won't have to TA a ton? If not, opt out of academia.

I had a half dozen tenure-track offers and decided on industry. Honestly, academia is not what it used to be. Lots of professors come close to killing their under-paid grad students so that they can spend 20% of their time on blue sky research ideas. I get that time and then some without throwing poor kids under the bus. Without even asking, really. And make 3x what I would've made as a slave driver to boot.

Academia sucks, especially if you want to do good research. Seriously, outside of tippy-top elite institutions that can get the very best and brightest phd students, colleges and universities are some of the absolute worst places to do research these days.

And if you want to teach CS, don't bother with a PhD. Just ad junct a bit on the side of an industry gig, do not-insanely-bad, and you'll be full time within a year or two. If you want. Which you very likely wont, because teaching one class on the side while engineering is a lot more fun than teaching full time. Teaching is exhausting, even for people who love teaching.

Having started at a lower ranked school and ended at a higher ranked school, I can give you the following advice (which mostly applies to technical fields). First, do not fall into the trap of thinking that where you get your PhD, or whether you get your PhD, is some kind of indication of your worth. What matters is the quality of your work. People at top schools can do mediocre research, and people at low-ranked schools can change an entire field. Do the best research work you can do; nobody is going to care where the work was done.

Second, set expectations with your advisor -- you are not there to further your advisor's career, you are pursuing your own career goals and are not just cheap labor. If you start doing random tasks that your advisor needs done, tasks that are not related to your own research, you will find yourself doing those tasks all the time. It is like any other job, you need to make it clear that you are not going to work outside of your role.

Finally, and most important of all, keep your dignity and remember that you can always take a more satisfying job (for better pay). Make sure you pick up a master's degree ~2 years into the PhD program, it helps if you want to leave. You should never feel like you are trapped; years spent in a PhD program will count as years of relevant employment at most tech companies (at least those I am familiar with). The only reason you need a PhD is if you want a tenure track position, and you should know that junior faculty face a new lineup of BS as they work towards tenure.

We try to make “not attending top schools” not as important. We most often fail in doing that, of course, but the thought at least should be there.

It's over for you. Cry yourself to sleep.