It’s not either/or, bc, it’s both.
If you only have $10k to invest, then you pop it into a tax-advantaged account (if you assume that your retirement tax bracket will be lower than your 33% today).
But once you have more income to invest, say, another $10k, and further assume that your tax-advantaged is maxed out, then you have to invest it in an after tax account. (Going with your example numbers, regardless of the fact 401k cap is higher than 10k.)
So the question become, what is more beneficial for each investment bucket of $10k: a) the tax-advantaged 10k and, b) the taxable 10k.
a) grows tax deferred until age 70 (or whenever you pull it out).
b) grows incurring taxes every year (unless you purchase a non-dividend stock like BRK).
And the RoT answer is to put your income-producing investments into a and your cap gain investments into b. Otherwise, you are paying tax annually on the dividends from your income producing investments.
If you put bonds into a and stocks into b, you’d have a 50/50 portfolio allocation.
btw: If you hold BRK in b or other non-dividend paying stock, you could even get by with no tax at all if stepped up basis when you die.