请教 retirement account Roth 403b vs Pre-tax 403b,no employer

no employer match for both of them.

Which one should I choose,

I understand that could depend  on my salary now vs after retirement incomes, so in that case preferably pre-tax.

But for roth 403b, the earnings will not be taxed, this is the good part of roth 403b.

So I see many people suggest roth 403b is better, but some also recommend pre-tax 403b?

Which one is better? Is my understanding correct?

Thanks,