I seem to click mostly with women a few years older than me... why this is, I'm not really sure. The older women I have been with have been somewhat... hmm, immature for their age, but that's not a very good word for it. Just young at heart I suppose, so with me being a grumpy old (young - 28) man and them being a silly older woman, it balances out a bit.
It doesn't really matter to me, as others have said it's the connection that matters, but if I had to say either or, I'd go for same age or older than me.