Now, I'm an engineer in background so originally UCLA was more just to satisfy my current advisor. However, during the visit I met an PI and lab that I completely loved. The attitudes, people, and research is exactly what I want to do with my graduate career. The advisor is also extremely well connected and very well known, meaning that finding employment afterwards shouldn't be a problem. I can see myself learning a huge amount and keeping in touch with him for a long time afterwards. I'd be doing mostly engineering and materials work in the lab, and many professors at my current institution have strongly recommended him.
The downside? I don't want a Chemistry degree, and I didn't really like the rest of the department. UCLA also has a large amount of hoops to jump through for the degree and a low retention rate. Plus, I'm just extremely worried about the job market for Chemistry phds right now, it just doesn't seem like something I should jump in to since I'm not sure what route I want to take after graduating. It seems like it might be a very long, hard slog without much payoff, and I really don't have an interest in pure chemistry. That seems to defeat the purpose of getting a phd in chemistry, which should be to set myself up for a career of chemistry. I've also lived in Southern California for my entire life so I'm wondering if a change of scenery would be beneficial.
Northwestern materials is exactly the kind of department I see myself excelling in. I clicked with the department as a whole to a much greater extent than at UCLA, and the general themes of the program much better fit my interests. It also has an extremely high retention rate and a very good time to degree average. I also loved Chicago when visiting. However, I didn't find a professor or lab I was as excited about to start in as at UCLA, but there were 5 or 6 I wouldn't mind working for.
At this point it really comes down to, do I choose the best advisor or best department?