As an investmment advisor, I always recommend using mutual funds vs. individual stocks. The reason being is that, with individual stocks you are tied to a single company (or a couple of companies) future. If one of those companies has a bad year that could dramatically reduce your portfolio. Also, in owning an individual stock, it is going to all be up to you to keep track of what is going with that company and do the buying or selling.
A mutual fund, gives you diversification to hundreds of companies. And if you are more broadly diversified, you could have a couple thousand comapanies that you are invested in. Therefore, if one of those companies goes down it will not have a dramatic affect on your portfolio. Also, with a mutual fund, you are also "hiring" an investment team that is doing all the detailed research on each company to know if they want to include it in fund.
ETFs can be nice inexpensive options (if your have them), but they are sometimes over-simplified. That is, they will invest in every stock in the S&P 500 without looking at removing some of the laggards, or increasing ownership on a leader.
There is a lot more on that, but I hope that helps explain a little bit of what to look for in your 401k.
P.S. Make sure you look at investments with a longer than 10 year track record. High returns have been easy over the last 5-7 years, but that eliminates 2008.