This is actual a complicated question. In truth, you are probably fine either way if you do a few things.
If you go to a "less tough" undergraduate program you will face stiffer competition getting in. However, going to a less rigorous college you will be fine if you do a few things. You definitely need a science major (bio, chem or biochem) and at least 3.5 or higher GPA/QPA .
I would also have a second major that shows where you interests lie, especially if you may not go into private practice after you graduate from vet school. Something like microbiology, nutrition, physical therapy.
Also, being bilingual will help immensely. So a minor in French, Spanish, Vietnamese, whatever is common where you are or want to be etc.
You will need more experience working or volunteering in vet med if you have an easier undergrad school. So make sure to start working at a clinic, wildlife rehab center or in the research dept at your school.
A tougher undergrad proves you can handle the course work at vet school. However, I would emphasis the debt crisis in veterinary medicine right now. Get the cheapest quality undergrad you possibly can and also the cheapest vet school education possible. Vet salaries can not support more than $75-100 k in educational debt and this is a crisis that is causing massive dissatisfaction in the veterinary field.
If you can't pay for college and vet school and will end up with more student loans than the amount I detailed, please consider scholarships such as the Army, CDC, etc. They pay for school and you owe them 3-5 years after but then you are free and have great contacts and experience.
Finally, make sure your undergrad degree could lead to a masters or Phd that you would consider doing as a career. This helps lessen the fear of what you will do if you don't get in and can lead to a degree that could help you get into vet school in the future. The average person applies 2-3 times to school before getting in. One of the best vets I've ever worked with applied 7 times before he got in.
Good luck and remember they are looking for people who can show that they can FINISH vet school. They want to see you can handle a lot of stress BEFORE they let you in.