All of them!
More specifically, it does depend a little on your goals. If you’re saving for the period of your retirement after pension access age (i.e. 58-60ish) then a SIPP is the best choice as it gives you free money.
If you will retire a bit sooner than pension access age, you’d want to build a “bridge fund” using an ISA. Or if you have money which can’t go into a SIPP (either because you’ve used up your SIPP allowance, or your income is “unpensionable” like rent from rental properties) then an ISA is the next best choice for your money.
If you have exhausted your tax-sheltered accounts for the year then the next best choice is a GIA. Even though it’s “taxable”, you still get allowances to use up in there – it just takes a bit more management.
Loving the 2026 RFS course. One thing that has cropped up for us is that we have too much in cash and our ISA allowances are already filled (as are our SIPP allowances), but the tax implications of a GIA are quite confusing and, to be honest, scary. Have you created, or do you plan to create, a session on running a GIA in an efficient, and HMRC compliant, manner? Thanks