I was inquiry which is better pretax or after tax for 401 k.?

Answer 1

As in many things regarding taxes, the answer is: It depends.

If you expect your tax rate to be lower when you withdraw your money, then pretax would be better.

If you expect your tax rate to be higher, paying the tax now would be better.

Answer 2

If your contributions go into a traditional 401(k), pre-tax is better. If you have the option of a Roth account inside your 401(k), it depends on your expected tax rate at retirement, and how close you are to retirement.