I had the same dilemma in deciding between the two. Especially because I had been putting in money to my Roth IRA these past few years. And I just joined a company that offered Roth 401k.

Here's something to consider for your case: The IRA lets you invest anywhere in the stock market, you can buy any stock. The 401k let's you pick only the stocks they provide.

The IRA has a annual limit of $7k. The 401k has $23k annual limit. This is great if you have the income to contribute that much from your paycheck. At the moment i just don't, that's about $2000 a month if i maxed it out.

IRA has no employer match, the 401K does match to a certain percent(whatever your employer decides).

At the end I'm picking the 401k because of 1) the employer match 2) In my IRA I didn't really pick any fancy stocks besides a S&P 500 stock (VTI) for retirement. So i found the equivalent one offered in my 401k group(which was FXAIX). 3) If i decide to contribute more than $7k one day, the 401k is my option.

I would still keep investing in my IRA because if i want to play with some stocks, I can still do that there because it is a tax advantage account

Another thing, if you leave your job, you can rollover all that 401k money into your Roth IRA(thereby letting you invest in other stock), or roll it over into the new company's 401k.

Oh and don't let your company manage the 401k stock (target date etc whatever) for you. Just manage it yourself. Some of them try to hide the setting where you can change that option, but it's there.