That depends entirely on who the members are and how much involvement they want in running the scheme. Personal preference comes into play as much as anything else, as well as the objectives you have in mind. Both pensions must abide by HMRC rules to ensure they do not incur tax charges. Both SIPP and SSAS still enjoy the same benefits and tax relief as traditional pensions. It is always advisable to speak to your financial advisor or accountant when looking to transfer your pensions to a SIPP or a SSAS.