charitable contribution

I think it is always better to make a QCD from the RMD.  Then the RMD isn't taxed as income.

It is hard without knowing your specific situation, but in general:

It is better to take a Qualified Charitable Distribution than have your charity as an itemized deduction.  First, your QCD takes the income out of your total income, which means it is effectively a state tax deduction for all states that begin their calculation of tax using the Federal Adjusted Gross Income.  Lowering your adjusted gross income also has other effects on your federal return, as it is the key number which determines eligibility for many tax credits and deductions - student loan interest, education credits, passive loss eligibility, etc.  In the last couple of years, Adjusted Gross Income determined whether or not you received a stimulus payment.  So any chance to lower your adjusted gross income can have very beneficial side effects.

As a practical matter, most people who are taking a QCD are retired or mostly retired; in general this means that if they have mortgage interest on their residence it is a lower than average amount.  For a married couple, the standard deduction with both spouses over age 65 was $27,800, which is a high number.  Since state and property tax deductions that apply to itemized deductions are capped at $10,000, it effectively means that (for most people) the standard deduction vs. itemized deduction evaluation is:  Do my charitable contributions plus my mortgage interest exceed $17,800?   If they do, you are probably itemizing your deductions.  But let's say you have $15,600 in charity and $5,000 in mortgage interest (and over $10k paid in property/state/local taxes).  Yes, you are itemizing your deductions and getting $30,000 in total deductions.  But if you gave $15,000 through a qualified charitable distribution and $600 in cash contributions to your charity and took the standard deduction, you would have a total deduction of $43,400:  $15,000 QCD PLUS $27,800 of standard deduction PLUS $600 charitable contribution that you can take even if you are using the standard deduction.  So you get an additional $13,400 of deduction by using the QCD option, and you might lower your state taxes too.