Should I go to engineering graduate school right after undergrad or after a few years of work experience?
Of the opinions you heard, most make sense to me. However the most important part is what you want to do. If you are eager to go into industry and want to try that, then go with that. If you prefer to do your graduate (and maybe later a PhD), then choose that. But do not plan too far ahead, i.e.: "I'll work 2 years, go to graduate school, do my PhD, and go back to industry." Real life does normally not work like that, and if you really are trying to reach these goals they might give you more stress and worries than help you.

I, after my master degree was kind of tired of University, and worked for a company during three years. After those three years I looked into different options (for personal and professional reasons), and decided to go back in research by doing a PhD.

Try to make a list of "pros and cons", and make a decision based on that.