If you believe the strong version of the market efficiency theory, none of these matters, just throw same darts at a list of companies. But I don't believe it, according to studies: companies with high (but not the biggest) dividends, those with low PE ratios and those with high return to equity; seem to outperform in comparison to average.
So buying an index fund, is fine, that seems to outperform the average funds manager, but its not hard to do better - if you follow the above principles.
A couple of years ago, I read about the superior performance of index funds, so I bought a couple (a standard, and a high dividend version of them), so I could compare with how I'm doing, and over the years I have held them, I have outperformed them (which was really a surprise, I expected to be beaten, and consequently I was just going to buy index funds)
So, I think the morale of this story, is that if you don't want to analyse companies, just buy index funds, but if you don't, and you can avoid 'hype', you can do better.