It would depend on several factors:
-- If my only tax-deferred option is a 401k (or even 2 of them for a couple), we can't put away $45k/yr tax-deferred.
-- If my company has no match and/or poor, expensive choices in its 401k plan, I might not want to use it.
-- How soon and how early I was expecting to retire. I might save more tax-deferred at age 20 than at age 50, for example.
-- Whether I am coming into an inheritance in the near future, and if so, whether it's in the form of an IRA or taxable.
-- My tax situation (worry about AMT? empty nester with no mortgage and very few deductions?).