401K vs. Roth IRA

Generally, it's best to invest in your 401K plan first, up to the amount your employer will match, then to invest in a Roth IRA. If you have additional funds to invest after making the maximum contribution to your Roth IRA, you should max out your 401K, and then invest in taxable accounts. There are always exceptions, however, so here are some points to consider when deciding the best order to invest your retirement funds:
Matching Contribution - many employers will provide a matching contribution when you elect to participate in the company 401K or other employer sponsored retirement plan. This is free money, and should be taken advantage of even if your 401K plan isn't the best due to poor investment choices, high expenses, etc. There is no matching contribution for a Roth IRA, so you should invest in your 401K up to the matching contribution first, before you invest in a Roth IRA.
Investment Choices - Most 401K plans have a limited number of investments to choose from. Roth IRAs can be opened just about anywhere: mutual fund companies, brokerage firms, banks, etc., which means your investment choices are unlimited. If your 401K plan has limited or poor investment selections to choose from, the Roth IRA may be the better choice (after you contribute enough to get the matching contribution in your 401K plan).
Taxes - although your 401K contributions are tax-deferred, which allows more of your money to go to work for you, money invested in a Roth IRA grows tax free. As long as you follow the rules, you may never pay taxes on the earnings in a Roth IRA. If you expect to be in a higher tax bracket when you retire, this could result in substantial tax savings.
Because withdrawals from a 401K account are taxed at your ordinary income tax rate, withdrawals could potentially push you into a higher tax bracket. If you have a combination of 401K and Roth IRA accounts, you have greater flexibility in choosing which account to withdraw from, which could allow for tax planning opportunities to help minimize your taxes during your retirement years.
One more note regarding taxes: 401K, traditional IRAs, and other employer sponsored retirement plans are subject to the Required Minimum Distribution rules; Roth IRAs are not. Again, having Roth IRAs in combination with your 401K accounts can provide tax planning opportunities not available to people who only have 401K accounts.
Withdrawals - your contributions to a Roth IRA are available to you penalty and tax-free at any time. Your earnings in a Roth IRA may also be withdrawn at any time. There is a 10% penalty, but this penalty may be waived under certain circumstances (disabled, first time homebuyer, qualified higher education expenses and more). Withdrawals from a 401K plan are much more restricted, as employers may or may not allow early withdrawals or loans.
Automatic investments - contributions to your 401K account are automatic since they come directly from your paycheck. This makes investing in your 401K easy and convenient, and after you've started contributing, most likely you'll no longer miss the money being invested. Investing in a Roth IRA takes more effort. Although many Roth IRA custodians will allow you to setup an automatic investment plan from your checking or savings account, it takes more discipline to invest in a Roth IRA than it does to invest in a 401K plan. If you think you don't have the discipline to invest in a Roth IRA account, then investing in a 401K plan (even a poor 401K plan) is better than not investing at all.

Though, everyone has own viewpoint, problems and situations...so....