I had two PhD offers and I chose this one mainly because my previous advisors recommended it. It is a presitigious university in an exciting and happening city and an experienced advisor who is a "good human being". All of these points, except university prestige, I still think are important parameters to make the choice. I would also look at the department structure and work culture - both of which are often better at public universities.
Course Curriculum
It is a relevant course curriculum but with a large focus on community and ecosystem ecology. Not a lot of wildlife. Some of the courses have field components and research is obviously a part of the work.
Exams
I took a general GRE and a TOEFL. But the general GRE requirement has been scrapped since. And the TOEFL can be replaced by a certificate of proficiency. My scores: GRE 165 verbal 169 quant 4.5 Writing; TOEFL 117/120
Placement
Jobs after PhD are usually post-docs and there are no companies recruiting from our department. Some people go on to work in conservation NGOs like WCS and TNC.
Events
There is a lot of activity on campus in a range of fields. There are several events and talks everyday. Club memberships can often be restricted to undergraduates, but plenty of grad opportunities as well. Some of the gym facilities are available to all, but the classes are paid. The libraries are excellent.
Scholarship
All incoming students at Columbia get a Dean's Fellowship. So I got that. Before that, I was supported by the CSIR Junior Research Fellowship and KVPY.
Faculty
The faculty to student ratio is about 1:5. Faculty are busy but approachable and the admin staff are helpful.
Hostel
No - I share an apartment outside. Rentals are generally expensive though.
