It's all personal preference. I've worked with students/graduates from all types of schools (3 yrs, 4 yrs, 6 yrs out of hs) and there really is no difference.
Personally, I am a person who gets burnt out really fast and needs time off to relax from studying. I would definitely choose 4 yrs because of this for the summers. However, if you are the type of can just study for YEARS non-stop, go for the 3 yr program..
When it's all said and done, I don't think it's much of a difference. Because in retail (at my store at least), I can't see the difference in quality of the pharmacists/recent graduates who went to 3 or 4 or 6 yr programs.