I think it depends from person to person. Looking back on my dating history, all of my relationships have been with guys
at least 2 years older than myself - the biggest age gap being 10 years. I have dated guys my own age of course, but I've always found that we're not really on the same wavelength. (I may be in my early 20s on the outside, but I'm actually 80 at heart).
I think it depends on what you're looking for in a relationship as well, and whether that person is 1) on the same page, and 2) whether you're happy with that person. If so, I don't think age differences really matter. (Provided it's all good and legal...
)