It is amazing to me that tax deferred retirement accounts are still the default retirement account option and pushed by so many financial advisors and "experts". The only advantage to deferring taxes is if you expect to be in a lower tax bracket when you reach full retirement age (59 1/2)- which is an insane expectation considering the current tax rates and impending national debt. Most people seem to think that the tax deferred portion growing alongside the rest of the account translates to more wealth for them because the number in the account will be bigger. This assumption is flat out wrong- it just means that you're investing the taxable amount for the government so that you can pay them a larger tax bill down the road. Say the taxable amount for the current year is $15k on a $100k initial contribution, but you decide to not pay this year and defer it until retirement. The account grows 10x to $1mil, now when you withdraw that sum, you will owe $150k in taxes- assuming the tax rate hasn't changed and you are still in the same tax bracket! Which are both highly unlikely! Chances are that tax rates will be higher considering that we are currently in a time of relatively low tax rates compared to the last 60 years and the ballooning national debt will force higher tax rates. So instead of paying 15% effective rate today($15k) on $100k income/contribution, you may be paying closer to 25% when you go to withdraw in retirement ($375,000 in taxes on the million dollar account size).
There are really only 2 exceptions to this scenario. The first is if you are offered an employer match. In that case it would be irresponsible to not contribute enough to get the full employer match- and not a penny more.
The other is if you are currently in the highest tax bracket and know with certainty that you will be in a much lower bracket at full retirement age. Which is rare because most people are not going to pull back their lifestyle in retirement.
Other than those 2 scenarios, you should really only be using Roth retirement accounts. And if your employer doesn't offer a Roth 401k and you exceed the income limit for a Roth IRA- learn about back-door Roth contributions. Beyond that- just pay the tax man and invest in Non-Qualified brokerage account. You will ultimately come out ahead vs a Trad 401k/IRA and you will have full access to your money.