My experience here is mostly based on having a daughter who will start in a DVM program in September. I guess we are a few years ahead on the same path.
My first reaction is that UIUC and UC Davis are both very strong universities for pre-vet. This does make it tough to decide between them.
Veterinary school is expensive. You need to budget for a full 8 years of university. It is a good plan to avoid taking on any debt at all for your bachelor’s degree. If you can save money for Vet school that would be even better.
Pre-vet classes will overlap quite a bit with premed classes. There will be many very strong students in these classes. You will need to work very hard and try to keep your GPA up as much as possible. My daughter ended up having several friends who were premed because she met them in the overlapping classes.
My daughter did very well in DVM program admissions. I think that a big part of this was her experience working with animals in a very wide range of situations. This included working on a farm with both large and small animals (probably more large ones), reaching inside cows multiple ways, helping out in emergency situations, doing some research with animals (no animals were harmed), working as a veterinary technician, and cleaning up after all of the above. She assisted with surgeries and with euthanasia. She helped baby cows being born. She also helped dealing with customers. Any of this experience would be helpful. Some of this can be gained as a job after you get your bachelor’s degree.
You should look at what sort of experience you can get at each of these schools. They probably will both have internship possibilities and may have some prevet summer programs.
I looked at what sort of students were accepted to the DVM programs that my daughter was applying to. They seem to have come from a very wide range of undergraduate schools and a wide range of majors.
What state are you from? Are you out of state for UC Davis? If so I am surprised that you would only be paying $22k per year. A full ride to UIUC sounds attractive to me.