It isn’t going to be one or the other (if they don’t offer a 401k, then you can use IRAs), unless you just make a bad choice. An employer can contribute to a 401k and also provide a pension (mine used to but I’ve been around long enough that I get both the pension and 401k with matching) but if I had a choice, I could pick a pension for example but also put money into an IRA for retirement that would normally go to a 401k.

If you absolutely had to pick one, it isn’t going to be the same answer for everyone. Amounts, what you’re able to contribute, matching, risks and tax situations are going to vary from person to person and their employer.

As far as controlling your money, some 401k’s allow some extra control, some don’t but most have a middle ground except for their company stock which you can usually directly buy. If you’re 401k allows general different ‘markets’ and/or ‘lifecycle’ buckets (they get more conservative on investment risk the closer you get to your retirement age) is, at the end of the day, all controlled by a broker and they are making the actual decision as to what to invest and how. Some plans may allow you to invest into individual stocks through the 401k’s brokerage though.

At the end of the day though, if all you had was a pension offered which you aren’t going to be contributing your income to, then you should invest in some sort of retirement plan yourself, be it an IRA, money market, bonds, CDs or whatever.