The three firms were declared the best providers for self-invested personal pensions by the consumer group, with savers awarding excellent customer scores and recognising their value for money.

In the wake of the pension freedoms, SIPPs have become an increasingly popular way for savers to build and manage their own retirement pot of shares, funds, investment trusts and other assets, often at a cheaper price than traditional pension providers.

To find the best options in the market, Which? surveyed more than 1,200 people about their SIPP providers and asked them to rate platforms across a range of factors, including investment information and online tools, as well as whether they would recommend it to others.

The consumer champion also reviewed the core fees that they charged across seven different pot sizes.

AJ Bell and Halifax both topped the table after they received an excellent overall customer score of 72%. Vanguard was in third place with 70%. All three firms were named as Which? Recommended Providers and were rated four stars out of five for their value for money by respondents.

AJ Bell and Vanguard in particular were recognised by Which? as being competitively priced because of low percentage-based platform fees, while Halifax’s charging structure means that it is the cheapest selection for pots of more than £120,000.

An AJ Bell customer described the service as “excellent and very easy to use”, while a recent switcher to AJ Bell said their new provider “was very much better than my previous experience.”

Despite only entering the market in February this year, Vanguard scored an impressive customer score of 70% and its simplified offering was rated highly for value for money.

But despite its low-cost offering, Vanguard investors only have access to a limited own brand selection of funds, not shares or investment trusts.

The lowest scorers

Meanwhile, James Hay and Bestinvest had the lowest customer scores in the survey, with 54% and 58% respectively. James Hay scored just one star for investment information, while Bestinvest was relatively expensive when Which? analysed its costs to investors.

Which? found the difference in costs could be significant. Annual costs for a £100,000 pot ranged from £180 to £450, while for a pot worth £500,000 switching from the most to the least expensive Sipp would save you £1,570 a year.

Choosing a Sipp means people taking on responsibility for building and managing their own investment portfolio, so savers will need to have the time and confidence to do this.

Jenny Ross, Which? money editor, said: “For experienced investors, these DIY pensions offer a cheap, flexible and straightforward way to save for retirement – but while there are plenty of options to choose from, it’s clear that some offer a much better deal than others.

“Our analysis shows that the top performers manage to combine great customer service with good value for money, so anyone unhappy with what they’re getting from their current provider should look at switching to one of these.”